diff --git a/dlls/d3dx8/d3dx8.spec b/dlls/d3dx8/d3dx8.spec
index 50d4cc3803b..82c958606d8 100644
--- a/dlls/d3dx8/d3dx8.spec
+++ b/dlls/d3dx8/d3dx8.spec
@@ -13,7 +13,7 @@
 @ stdcall D3DXVec3TransformCoord(ptr ptr ptr)
 @ stdcall D3DXVec3TransformNormal(ptr ptr ptr)
 @ stdcall D3DXVec3Project(ptr ptr ptr ptr ptr ptr)
-@ stub D3DXVec3Unproject
+@ stdcall D3DXVec3Unproject(ptr ptr ptr ptr ptr ptr)
 @ stdcall D3DXVec4Cross(ptr ptr ptr ptr)
 @ stdcall D3DXVec4Normalize(ptr ptr)
 @ stdcall D3DXVec4Hermite(ptr ptr ptr ptr ptr long)
diff --git a/dlls/d3dx8/math.c b/dlls/d3dx8/math.c
index ddc2df250cf..7f965838b13 100644
--- a/dlls/d3dx8/math.c
+++ b/dlls/d3dx8/math.c
@@ -606,6 +606,21 @@ D3DXVECTOR3* WINAPI D3DXVec3TransformNormal(D3DXVECTOR3 *pout, CONST D3DXVECTOR3
 
 }
 
+D3DXVECTOR3* WINAPI D3DXVec3Unproject(D3DXVECTOR3 *pout, CONST D3DXVECTOR3 *pv, CONST D3DVIEWPORT8 *pviewport, CONST D3DXMATRIX *pprojection, CONST D3DXMATRIX *pview, CONST D3DXMATRIX *pworld)
+{
+    D3DXMATRIX m1, m2, m3;
+    D3DXVECTOR3 vec;
+
+    D3DXMatrixMultiply(&m1, pworld, pview);
+    D3DXMatrixMultiply(&m2, &m1, pprojection);
+    D3DXMatrixInverse(&m3, NULL, &m2);
+    vec.x = 2.0f * ( pv->x - pviewport->X ) / pviewport->Width - 1.0f;
+    vec.y = 1.0f - 2.0f * ( pv->y - pviewport->Y ) / pviewport->Height;
+    vec.z = ( pv->z - pviewport->MinZ) / ( pviewport->MaxZ - pviewport->MinZ );
+    D3DXVec3TransformCoord(pout, &vec, &m3);
+    return pout;
+}
+
 /*_________________D3DXVec4_____________________*/
 
 D3DXVECTOR4* WINAPI D3DXVec4BaryCentric(D3DXVECTOR4 *pout, CONST D3DXVECTOR4 *pv1, CONST D3DXVECTOR4 *pv2, CONST D3DXVECTOR4 *pv3, FLOAT f, FLOAT g)
diff --git a/dlls/d3dx8/tests/math.c b/dlls/d3dx8/tests/math.c
index 70e5240afb2..65a0e5a670d 100644
--- a/dlls/d3dx8/tests/math.c
+++ b/dlls/d3dx8/tests/math.c
@@ -878,6 +878,12 @@ static void D3X8Vector3Test(void)
     expectedvec.x = 57.0f; expectedvec.y = 74.0f; expectedvec.z = 91.0f;
     D3DXVec3TransformNormal(&gotvec,&u,&mat);
     expect_vec3(expectedvec,gotvec);
+
+/*_______________D3DXVec3Unproject_________________________*/
+    expectedvec.x = -2.913411f; expectedvec.y = 1.593215f; expectedvec.z = 0.380724f;
+    D3DXMatrixPerspectiveFovLH(&projection,D3DX_PI/4.0f,20.0f/17.0f,1.0f,1000.0f);
+    D3DXVec3Unproject(&gotvec,&u,&viewport,&projection,&view,&world);
+    expect_vec3(expectedvec,gotvec);
 }
 
 static void D3X8Vector4Test(void)
diff --git a/include/d3dx8math.h b/include/d3dx8math.h
index 93acf7babff..99164903055 100644
--- a/include/d3dx8math.h
+++ b/include/d3dx8math.h
@@ -304,6 +304,7 @@ D3DXVECTOR3* WINAPI D3DXVec3Project(D3DXVECTOR3 *pout, CONST D3DXVECTOR3 *pv, CO
 D3DXVECTOR4* WINAPI D3DXVec3Transform(D3DXVECTOR4 *pout, CONST D3DXVECTOR3 *pv, CONST D3DXMATRIX *pm);
 D3DXVECTOR3* WINAPI D3DXVec3TransformCoord(D3DXVECTOR3 *pout, CONST D3DXVECTOR3 *pv, CONST D3DXMATRIX *pm);
 D3DXVECTOR3* WINAPI D3DXVec3TransformNormal(D3DXVECTOR3 *pout, CONST D3DXVECTOR3 *pv, CONST D3DXMATRIX *pm);
+D3DXVECTOR3* WINAPI D3DXVec3Unproject(D3DXVECTOR3 *pout, CONST D3DXVECTOR3 *pv, CONST D3DVIEWPORT8 *pviewport, CONST D3DXMATRIX *pprojection, CONST D3DXMATRIX *pview, CONST D3DXMATRIX *pworld);
 
 D3DXVECTOR4* WINAPI D3DXVec4BaryCentric(D3DXVECTOR4 *pout, CONST D3DXVECTOR4 *pv1, CONST D3DXVECTOR4 *pv2, CONST D3DXVECTOR4 *pv3, FLOAT f, FLOAT g);
 D3DXVECTOR4* WINAPI D3DXVec4CatmullRom(D3DXVECTOR4 *pout, CONST D3DXVECTOR4 *pv0, CONST D3DXVECTOR4 *pv1, CONST D3DXVECTOR4 *pv2, CONST D3DXVECTOR4 *pv3, FLOAT s);