The living polymerization of propene was conducted at 0degreesC using a chelating diamide complex of titanium combined with dried modified methylaluminoxane from which free trialkylaluminium compounds were removed much as possible before use. The number-average molecular weight of the statistically poly(propylene) produced increased almost linearly with increasing polymerization time accompanied by a narrowing of the molecular weight distribution from 1.34 to 1.16.