Optically pure (R)- and (S)-N-alkyl-1-cyclohexyl-2-phenylethylamine hydrochlorides (9a-r)were synthesized from (R)- and (S)-phenylglycine by means of a simple procedure. The analgesic activity of these compounds was evaluated by the acetic acid writhing method, and 9e, 9f, 9i-k, and 9m showed more potent activity than (-)-pentazocine hydrochloride. Moreover, the analgesic activities of 9a-e, 9h, 9i, 9m, and 9o-r were not antagonized by naloxone.