The polymerization of N-propargylamides (HCdropCCH(2)NHCOR, R = i-Pr (1), i-Bu (2), or n-Pen (3)) with a Rh vinyl complex (4) was examined. The polymerization of 2 in chloroform in the presence of triphenylphosphine yielded polymer with a relatively narrow molecular weight distribution (M-n = 17 300, M-w/M-n = 1.36). The first-order plot based on the time profile of polymerization at 0 degreesC was linear, and the second monomer feed was also consumed completely in multistage polymerization. These results indicate that this polymerization has a livinglike nature. Further, a block copolymer was successfully prepared from monomers 2 and 3.