Most developing and transition countries adopted statutes prohibiting anticompetitive agreements and abusive practices during the 1980's and 1990's. The effectiveness of these laws is nevertheless widely debated. This paper contributes to the literature by conducting an event study of the adoption of Russian competition laws in the early years of transition, the subsequent economic developments and the legislative reform process of 2002-2006. An examination of the substantive prohibitions and enforcement data reveals that Russian competition laws relied on complex standards and imposed weak constraints on anticompetitive practices. The more recent shift to simpler and more predictable per se prohibitions against collusive agreements substantiates this hypothesis. The evidence has implications for the design of regulatory regimes in other countries with laws similar to those operative in Russia during the transition process.