Abstract In the course of work on the preparation of the sulfur isosters (I a ) of lysergic acid (I b ), a literature search was made for other analogs of lysergic acid to see what types of molecular modification had already been applied to this structure. The following review of the published studies on analogs of lysergic acid is the result of this search. Most of these analogs consist of partial structures of lysergic acid or derivatives thereof, in which one or more of the rings have been opened or dissected away to discover the smallest fragment of the polycyclic system that might retain biological activity. The analogs are discussed in structural categories rather than by biological activity groups.