The present study deals with the copolymerization of an amino acid-based acetylene, N-(tert-butoxycarbonyl)-L-alanine N'-propargylamide (L-1A) with the optical isomer (D-1A), achiral hexanoic acid N-propargylamide (2A), and pivalic acid N-propargylamide (3A), and chiroptical properties of the copolymers. The copolymerization catalyzed by (nbd)Rh+[eta(6)-C6H5B-(C6H5)(3)] afforded copolymers with number-average molecular weights over 104 in good yields. Nonlinear relationships were observed in the specific rotation and CD and UV-vis spectroscopies with respect to the L-1A content in feed. For instance, poly(L-1A-co-D-1A)s incorporated with 12.5% of either optical isomer (75% ee) exhibited almost the same optical properties as those of the homopolymers. Chiral amplification was observed in the copolymerization of L-1A with the achiral monomers. The specific rotation of poly(L-1A-co-2A) with 45% L-1A unit was practically the same as that of poly(L-1A). The copolymers of L-1A and 3A with an L-1A content in feed as low as 12% exhibited nearly the same helix content as the homopolymer of L-1A did.