AbstractA number of solvent compounds that were tested in Saccharomyces cerevisiae were potent inducers of aneuploidy, although they did not induce any other genetic effects. As an extention of these earlier findings, 1‐methyl‐2‐pyrrolidinone was tested and was found to induce aneuploidy. Several structurally related compounds were also tested; 2‐pyrrolidinone induced aneuploidy, but succinimide, pyrrolidine, 1‐methylpyrrolidine, 1‐methyl‐3‐pyrrolidinol, and 2‐pyrrolidineethanol did not. Maleimide and its N‐hydroxy, N‐methyl, and N‐ethyl derivatives were also negative for aneuploidy induction.