A comparative molecular similarity indices analysis (CoMSIA) of a set of 29 imidazolyl and N-pyrrolyl heptenoates have been performed to find out the structural requirements for 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) inhibitory activity. The HMG like side chain, a common moiety of statins, was used to align the molecules. The results guide to design new chemical entities with high potency.