SynopsisMagnesium aluminum alkyls containing higher (C,-C,,,) radicals were studied as components of Ziegler-Natta catalysts in styrene polymerization. The effects of alkyl radical length and MgR, contents in the components mentioned on the degree of TiCl, reduction and stereospecific activity of the catalysts were investigated. The components studied exhibited high reducing (for TiCl, ) and catalytic activities. Molecular weight of the synthesized isotactic polystyrene was abnormally high.