Hi Marta, You can use vtkMatrix4x4 and do something like this; vtkMatrix4x4 vtk_matrix vtk_matrix SetElement 1 1 matlab_matrix[1][1] ... and so on up to element 3 3. Hope this helps, Glen Marta wrote: > How can I pass a matlab variable (3*3 matrix, whiht an image) to vtk, > when programming in tcl/tk? > > > Thank you in advanced. Marta