The radical polymerization of N-tert-butyl-N-allylacrylamide (t-BAA) was carried out in a dimethyl sulfoxide/H2O mixture in the presence of beta-cyclodextrin (beta-CD) The polymerization proceeded with the complete cyclization of the t-BAA unit and yielded optically active poly(t-BAA). The IR spectrum of the obtained polymer showed that the cyclic structure in the polymer was a five-membered ring. The optical activity of poly(t-BAA) increased with an increasing molar ratio of beta-CD to the t-BAA monomer. The interaction of beta-CD with t-BAA was confirmed by H-1 NMR and C-13 NMR analyses of the polymerization system. It is suggested that interaction of the t-BAA monomer with the hydrophobic cavity of beta-CD plays an important role in the asymmetric cyclopolymerization of t-BAA. The radical copolymerization of t-BAA with styrene (St), methyl methacrylate, ethyl methacrylate, or benzyl methacrylate (BMA) also produced optically active copolymers with a cyclic structure from the t-BAA unit. St and BMA carrying a phenyl group were predicted to compete with t-BAA for interaction with beta-CD in the copolymerization system.