he program ORTOCARTAN can calculate the curvature tensors (Riemann, Ricci, Einstein and Weyl) from a given orthonormal tetrad representation of the metric tensor. It was first announced in 1981, but since then has undergone several extensions and transplants onto other computers. This article reviews the current status of the program from the point of view of a user. The following topics are discussed: the problems that the program can be applied to, the special features of the algorithms that make the program powerful, the technical requirements to run the program and two simple examples of applications.