The effects of several nucleophilic agents-triethylamine, pyridine, ethyl ether and tetrahydrofuran-on the stercospecific polymerization of butadiene catalyzed by titanium tetraiodide and triisobutyl aluminum have been studied.It has been indicated that triethylamine or pyridine exerts almost no effect on the polymerization, when its quantity(in mole) introduced is less than that of triisobutyl aluminum;but inhibits the polymerization, when its quantity is larger than that of the whole catalyst.Tetrahydrofuran readily inhibits the polymerization, when its quantity(in mole) applied approaches twice that of titanium tetraiodide.Ethyl ether does not inhibit the polymerization, but changes the microstructure of the polybutadiene obtained from cis-l, 4-form to trans-l, 4-form, while keeping the content of the 1, 2-form constant.The results may be interpreted by different stabilities of the complexes formed between nucleophilic agents and the components of the catalyst.