Smallworld, I tend to agree with trav in that Carrara will do some wierd things with tri'd meshes. For the most part if the polys are coplanar, then the algorithm will de-tri a good portion of the mesh and save you a lot of time. If, however your meshes are based upon a lot of splines then there may be a lot of manual clean-up to make it look right. I re-did some of my older meshes with the untriangulate command and one of them was based on a polyhedron to begin with. That one was a mess to clean as the co-planar faces were in areas that I didn't want to un-tri. I ended up re-doing the mesh, but before I did, the command had shaved the poly count by almost half! This is not to say that it won't work for you. Like trav said, demo it and see what it can do for you. Ken