New optically pure (1S, 1'S)-and (1R, 1'R)-1-cycloalkyl-N-2'-hydroxy-1'-isopropylethyl-2-phenylethylamine hydrochlorides (3a-j) were synthesized in good yields. The analgesic activities of these hydrochlorides were evaluated by the acetic acid writhing method and the bradykinin-induced flexor reflex method. The structure of 3f'·HCl was elucidated by X-ray analysis. The relationship between the analgesic activity and the conformation of the 1-2 bond of these amines is discussed.