diff --git a/changes.txt b/changes.txt
index f6fbfc03..daa16e6c 100644
--- a/changes.txt
+++ b/changes.txt
@@ -1,5 +1,10 @@
 Changes in 1.8 (??.??.2011)
 
+ - quaternion conversions to and from matrix4 no longer invert rotations. 
+   To test if your code was affected by this you can set IRR_TEST_BROKEN_QUATERNION_USE in quaternion.h and try to compile your application.
+   Then on all compile-errors when you pass the matrix to the quaternion you can replace the matrix transposed matrix.
+   For all errors you get on getMatrix() you can use quaternion::getMatrix_transposed instead.
+
  - CGUIEnvironment::loadGui - loading a gui into a target-element no longer messes up when the gui-file contained guienvironment serialization.
 
  - Colladawriter now exports materials per node when those are used in Irrlicht
diff --git a/include/IAnimatedMeshMD3.h b/include/IAnimatedMeshMD3.h
index 0ff544a8..a9937620 100644
--- a/include/IAnimatedMeshMD3.h
+++ b/include/IAnimatedMeshMD3.h
@@ -166,10 +166,6 @@ namespace scene
 		SMD3QuaternionTag( const core::stringc& name )
 			: Name ( name ) {}
 
-		// construct from a matrix
-		SMD3QuaternionTag ( const core::stringc& name, const core::matrix4 &m )
-			: Name(name), position(m.getTranslation()), rotation(m) {}
-
 		// construct from a position and euler angles in degrees
 		SMD3QuaternionTag ( const core::vector3df &pos, const core::vector3df &angle )
 			: position(pos), rotation(angle * core::DEGTORAD) {}
diff --git a/include/quaternion.h b/include/quaternion.h
index 76902f8c..5a0fed11 100644
--- a/include/quaternion.h
+++ b/include/quaternion.h
@@ -10,6 +10,11 @@
 #include "matrix4.h"
 #include "vector3d.h"
 
+// Between Irrlicht 1.7 and Irrlicht 1.8 the quaternion-matrix conversions got fixed.
+// This define disables all involved functions completely to allow finding all places 
+// where the wrong conversions had been in use.
+#define IRR_TEST_BROKEN_QUATERNION_USE 0
+
 namespace irr
 {
 namespace core
@@ -34,8 +39,10 @@ class quaternion
 		//! Constructor which converts euler angles (radians) to a quaternion
 		quaternion(const vector3df& vec);
 
+#if !IRR_TEST_BROKEN_QUATERNION_USE
 		//! Constructor which converts a matrix to a quaternion
 		quaternion(const matrix4& mat);
+#endif
 
 		//! Equalilty operator
 		bool operator==(const quaternion& other) const;
@@ -46,8 +53,10 @@ class quaternion
 		//! Assignment operator
 		inline quaternion& operator=(const quaternion& other);
 
+#if !IRR_TEST_BROKEN_QUATERNION_USE
 		//! Matrix assignment operator
 		inline quaternion& operator=(const matrix4& other);
+#endif
 
 		//! Add operator
 		quaternion operator+(const quaternion& other) const;
@@ -89,8 +98,10 @@ class quaternion
 		//! Normalizes the quaternion
 		inline quaternion& normalize();
 
+#if !IRR_TEST_BROKEN_QUATERNION_USE
 		//! Creates a matrix from this quaternion
 		matrix4 getMatrix() const;
+#endif 
 
 		//! Creates a matrix from this quaternion
 		void getMatrix( matrix4 &dest, const core::vector3df &translation ) const;
@@ -185,13 +196,13 @@ inline quaternion::quaternion(const vector3df& vec)
 	set(vec.X,vec.Y,vec.Z);
 }
 
-
+#if !IRR_TEST_BROKEN_QUATERNION_USE
 // Constructor which converts a matrix to a quaternion
 inline quaternion::quaternion(const matrix4& mat)
 {
 	(*this) = mat;
 }
-
+#endif
 
 // equal operator
 inline bool quaternion::operator==(const quaternion& other) const
@@ -218,7 +229,7 @@ inline quaternion& quaternion::operator=(const quaternion& other)
 	return *this;
 }
 
-
+#if !IRR_TEST_BROKEN_QUATERNION_USE
 // matrix assignment operator
 inline quaternion& quaternion::operator=(const matrix4& m)
 {
@@ -229,9 +240,9 @@ inline quaternion& quaternion::operator=(const matrix4& m)
 		const f32 scale = sqrtf(diag) * 2.0f; // get scale from diagonal
 
 		// TODO: speed this up
-		X = ( m(2,1) - m(1,2)) / scale;
-		Y = ( m(0,2) - m(2,0)) / scale;
-		Z = ( m(1,0) - m(0,1)) / scale;
+		X = ( m(1,2) - m(2,1)) / scale;
+		Y = ( m(2,0) - m(0,2)) / scale;
+		Z = ( m(0,1) - m(1,0)) / scale;
 		W = 0.25f * scale;
 	}
 	else
@@ -244,9 +255,9 @@ inline quaternion& quaternion::operator=(const matrix4& m)
 
 			// TODO: speed this up
 			X = 0.25f * scale;
-			Y = (m(0,1) + m(1,0)) / scale;
-			Z = (m(2,0) + m(0,2)) / scale;
-			W = (m(2,1) - m(1,2)) / scale;
+			Y = (m(1,0) + m(0,1)) / scale;
+			Z = (m(0,2) + m(2,0)) / scale;
+			W = (m(1,2) - m(2,1)) / scale;
 		}
 		else if ( m(1,1) > m(2,2))
 		{
@@ -255,10 +266,10 @@ inline quaternion& quaternion::operator=(const matrix4& m)
 			const f32 scale = sqrtf( 1.0f + m(1,1) - m(0,0) - m(2,2)) * 2.0f;
 
 			// TODO: speed this up
-			X = (m(0,1) + m(1,0) ) / scale;
+			X = (m(1,0) + m(0,1) ) / scale;
 			Y = 0.25f * scale;
-			Z = (m(1,2) + m(2,1) ) / scale;
-			W = (m(0,2) - m(2,0) ) / scale;
+			Z = (m(2,1) + m(1,2) ) / scale;
+			W = (m(2,0) - m(0,2) ) / scale;
 		}
 		else
 		{
@@ -267,16 +278,16 @@ inline quaternion& quaternion::operator=(const matrix4& m)
 			const f32 scale = sqrtf( 1.0f + m(2,2) - m(0,0) - m(1,1)) * 2.0f;
 
 			// TODO: speed this up
-			X = (m(0,2) + m(2,0)) / scale;
-			Y = (m(1,2) + m(2,1)) / scale;
+			X = (m(2,0) + m(0,2)) / scale;
+			Y = (m(2,1) + m(1,2)) / scale;
 			Z = 0.25f * scale;
-			W = (m(1,0) - m(0,1)) / scale;
+			W = (m(0,1) - m(1,0)) / scale;
 		}
 	}
 
 	return normalize();
 }
-
+#endif
 
 // multiplication operator
 inline quaternion quaternion::operator*(const quaternion& other) const
@@ -320,15 +331,15 @@ inline quaternion quaternion::operator+(const quaternion& b) const
 	return quaternion(X+b.X, Y+b.Y, Z+b.Z, W+b.W);
 }
 
-
+#if !IRR_TEST_BROKEN_QUATERNION_USE
 // Creates a matrix from this quaternion
 inline matrix4 quaternion::getMatrix() const
 {
 	core::matrix4 m;
-	getMatrix_transposed(m);
+	getMatrix(m, core::vector3df(0,0,0));
 	return m;
 }
-
+#endif
 
 /*!
 	Creates a matrix from this quaternion
diff --git a/source/Irrlicht/CB3DMeshFileLoader.cpp b/source/Irrlicht/CB3DMeshFileLoader.cpp
index c1798161..fd4df43a 100644
--- a/source/Irrlicht/CB3DMeshFileLoader.cpp
+++ b/source/Irrlicht/CB3DMeshFileLoader.cpp
@@ -177,7 +177,8 @@ bool CB3DMeshFileLoader::readChunkNODE(CSkinnedMesh::SJoint *inJoint)
 	positionMatrix.setTranslation( joint->Animatedposition );
 	core::matrix4 scaleMatrix;
 	scaleMatrix.setScale( joint->Animatedscale );
-	core::matrix4 rotationMatrix = joint->Animatedrotation.getMatrix();
+	core::matrix4 rotationMatrix;
+	joint->Animatedrotation.getMatrix_transposed(rotationMatrix);
 
 	joint->LocalMatrix = positionMatrix * rotationMatrix * scaleMatrix;
 
diff --git a/source/Irrlicht/CMS3DMeshFileLoader.cpp b/source/Irrlicht/CMS3DMeshFileLoader.cpp
index ed112073..558c4bfa 100644
--- a/source/Irrlicht/CMS3DMeshFileLoader.cpp
+++ b/source/Irrlicht/CMS3DMeshFileLoader.cpp
@@ -501,7 +501,9 @@ bool CMS3DMeshFileLoader::load(io::IReadFile* file)
 
 			tmpMatrix=jnt->LocalMatrix*tmpMatrix;
 
-			k->rotation  = core::quaternion(tmpMatrix);
+			// IRR_TEST_BROKEN_QUATERNION_USE: TODO - switched from tmpMatrix to tmpMatrix.getTransposed() for downward compatibility. 
+			//								   Not tested so far if this was correct or wrong before quaternion fix!
+			k->rotation  = core::quaternion(tmpMatrix.getTransposed());
 		}
 
 		// get translation keyframes
diff --git a/source/Irrlicht/COgreMeshFileLoader.cpp b/source/Irrlicht/COgreMeshFileLoader.cpp
index 063d67a7..97bf7504 100644
--- a/source/Irrlicht/COgreMeshFileLoader.cpp
+++ b/source/Irrlicht/COgreMeshFileLoader.cpp
@@ -773,7 +773,10 @@ void COgreMeshFileLoader::composeObject(void)
 			ISkinnedMesh::SJoint* joint = m->addJoint();
 			joint->Name=Skeleton.Bones[i].Name;
 
-			joint->LocalMatrix = Skeleton.Bones[i].Orientation.getMatrix();
+			// IRR_TEST_BROKEN_QUATERNION_USE: TODO - switched to getMatrix_transposed instead of getMatrix for downward compatibility. 
+			//								   Not tested so far if this was correct or wrong before quaternion fix!
+			Skeleton.Bones[i].Orientation.getMatrix_transposed(joint->LocalMatrix);
+
 			if (Skeleton.Bones[i].Scale != core::vector3df(1,1,1))
 			{
 				core::matrix4 scaleMatrix;
@@ -823,7 +826,11 @@ void COgreMeshFileLoader::composeObject(void)
 				poskey->position=keyjoint->LocalMatrix.getTranslation()+frame.Position;
 				ISkinnedMesh::SRotationKey* rotkey = m->addRotationKey(keyjoint);
 				rotkey->frame=frame.Time*25;
-				rotkey->rotation=core::quaternion(keyjoint->LocalMatrix)*frame.Orientation;
+
+				// IRR_TEST_BROKEN_QUATERNION_USE: TODO - switched from keyjoint->LocalMatrix to keyjoint->LocalMatrix.getTransposed() for downward compatibility. 
+				//								   Not tested so far if this was correct or wrong before quaternion fix!
+				rotkey->rotation=core::quaternion(keyjoint->LocalMatrix.getTransposed())*frame.Orientation;
+
 				ISkinnedMesh::SScaleKey* scalekey = m->addScaleKey(keyjoint);
 				scalekey->frame=frame.Time*25;
 				scalekey->scale=frame.Scale;
diff --git a/source/Irrlicht/CSkinnedMesh.cpp b/source/Irrlicht/CSkinnedMesh.cpp
index 915fcbf8..98b92108 100644
--- a/source/Irrlicht/CSkinnedMesh.cpp
+++ b/source/Irrlicht/CSkinnedMesh.cpp
@@ -167,7 +167,9 @@ void CSkinnedMesh::buildAllLocalAnimatedMatrices()
 		{
 			joint->GlobalSkinningSpace=false;
 
-			joint->LocalAnimatedMatrix=joint->Animatedrotation.getMatrix();
+			// IRR_TEST_BROKEN_QUATERNION_USE: TODO - switched to getMatrix_transposed instead of getMatrix for downward compatibility. 
+			//								   Not tested so far if this was correct or wrong before quaternion fix!
+			joint->Animatedrotation.getMatrix_transposed(joint->LocalAnimatedMatrix);
 
 			// --- joint->LocalAnimatedMatrix *= joint->Animatedrotation.getMatrix() ---
 			f32 *m1 = joint->LocalAnimatedMatrix.pointer();
diff --git a/source/Irrlicht/CXMeshFileLoader.cpp b/source/Irrlicht/CXMeshFileLoader.cpp
index 0629cbd6..a40bb677 100644
--- a/source/Irrlicht/CXMeshFileLoader.cpp
+++ b/source/Irrlicht/CXMeshFileLoader.cpp
@@ -1877,8 +1877,10 @@ bool CXMeshFileLoader::parseDataObjectAnimationKey(ISkinnedMesh::SJoint *joint)
 
 				ISkinnedMesh::SRotationKey *keyR=AnimatedMesh->addRotationKey(joint);
 				keyR->frame=time;
-				keyR->rotation= core::quaternion(mat);
 
+				// IRR_TEST_BROKEN_QUATERNION_USE: TODO - switched from mat to mat.getTransposed() for downward compatibility. 
+				//								   Not tested so far if this was correct or wrong before quaternion fix!
+				keyR->rotation= core::quaternion(mat.getTransposed());
 
 				ISkinnedMesh::SPositionKey *keyP=AnimatedMesh->addPositionKey(joint);
 				keyP->frame=time;