A simple algorithm for the search of anti-Bredt molecular structures is described. It relies on a topological criterion and requires neither the starch of the smallest set of smallest rings of the molecular graph nor adjacency matrix manipulation. This algorithm, first implemented in Prolog and then in C language, is used in the LSD program (logic for structure determination) to discard unrealistic structures. The present article is the first report of an attempt to sort computer-generated organic structures according to this type of steric constraint.