The non-conjugated poly (3,3-dimethyl-1-butyne) and poly (1-trimethylsilyl)-1-propyne were prepared by metathesis catalysts and the polymerization was monitored for molecular weight by GPC and monomer conversion by GC. Both the 1-(trimethylsilyl)-1-propyne and 3,3-dimethyl-1-butyne gave a linear relationship with number average molecular weight versus conversion and number average molecular weight versus monomer to initiator ratio. The 1-(trimethylsilyl)-1-propyne failed to polymerize beyond 100% conversion. The 3,3-dimethyl-1-butyne, however, gave conversion to 300%, with GPC data clearly showing the continuation of propagation from the living polymer chain. The living character of these polymerizations seems to be the result of both the lack of backbiting which can occur only from a cis-cisoidal growing chain, and the lack of interchain reactions. Both the cis-cisoidal configuration and the interchain reactions are prohibited for steric reasons.