AbstractOptically active copolymers of l‐menthyl methacrylate or l‐menthyl vinyl ether with maleic anhydride or N‐(p‐tolyl)maleimide were prepared. The optical activity of the co‐polymers of l‐menthyl methacrylate was almost proportional to the contents of l‐menthyl methacrylate units in the copolymers, and after removal of the optically active side groups by hydrolysis, the optical activity disappeared. On the contrary, the optical activity of the copolymers of l‐menthyl vinyl ether was considerably lower than the proportionality, and after removal of the side groups, optical activity opposite to the parent copolymers was observed. The cause for asymmetric induction was ascribed to the rigidity of the polymer chain.