It is of importance in ultrasonic NDE to know how crack roughness effects the quality of inspection. Rough crack face was modeled in the past as a mosaic of large triangles using the Kirchhoff approximation. On the other hand, until now rough crack edge was modeled only under assumption of small perturbation. In this paper, in the spirit of the triangular facet model we model rough crack edge as a polygonal line and then apply the Isakovich approach which was developed for scatter from rough surfaces and is also based on the Kirchhoff approximation. For simplicity, we deal with a planar crack. © 2003 American Institute of Physics