AbstractThe 5‐HT1aand 5‐HT2receptor affinity of a set of 44N‐alkylated 1‐arylpiperazines and their analogs has been analyzed: then‐hexyl derivatives were the most potent and the most selective 5‐HT1aligands of all the investigatedN‐alkyl homologues. The alkyl chain may stablize the 5‐HT1areceptor‐ligand complex by hydrophobic forces. A set of the alkyl substituent contributions (Cht1a) for prediction of the 5‐HT1aaffinity ofN‐alkyl derivatives of 1‐arylpiperazines and related compounds have been defined on the basis of