This article presents a preliminary assessment of the impact produced by the 2003 Political Reform on the Colombian electoral and political parties systems. The assessment is based on a comparative analysis of the electoral results for the House of Representatives in the 2002 and 2006 elections. Specifically, the article evaluates the effects of the new set of rules according to its main goals: reducing the number of political parties, strengthening the surviving parties and guaranteeing more representativeness in the seat allocation process. It must be noted that this article offers a preliminary balance of a reform adopted only 3 years ago; therefore, it can not be evaluated in a definitive way.