The preparation of cis- and trans-1,3,5-triisocyanatocyclohexane is described. The coupling constantsJAB,JAX> andJBX were obtained from the NMR spectrum of the cis-isomer. Both isomers were polymerized using sodium cyanide in N,N-dimethylformamide as initiator. The evidence indicated that cyclopolymerization had occurred and, in both cases, predominantly bicyclic structures obtained.