NURBS (Non uniform rational B-spline) is a powerful and often used method for a mathematical description of curves, surfaces and bodies in general. By using NURBS-surfaces an accurate object description can be kept further into the calculations of radar cross section. The faceting, which is still ultimately needed, can be more easily adjusted on demand. We report here on a NURBS-surface implementation using physical optics (PO) calculations in Matlab. The code has been validated against analytic PO expressions and commercial PO code. A study of the convergence as a circular disc is approximated using progressively finer faceting was also done.- There is a potential for the development of an efficient tool for RCS calculation. However, since the code is intended for a preliminary evaluation of NURBS it is presently lacking e.g. shadowing algorithms. This leads to restrictions on the allowed model geometries.