I am trying to get only the curve that lies on the trimmed surface. In this case I have a trimmed spherical face and I am intersecting it with a plane that coincident with the axis of revolution. My problem is that the curve that results from ISurface:IntersectSurface ends up being the complete circle for the untrimmed sphere. (ie the curve parameters go from 0 to 2*pi) Is there an easy way to end up with the only the part that lies on the trimmed portion of the surface (like you would get if you inserted an intersection curve in a sketch). Right now I'm thinking I may have to get the edge loops for the face and manually trim the curve.