Although the primaries have been popularized as the mechanism for selecting candidates more open and participatory, often generate the opposite effect, strengthening the personalizationof politics and not the institutionalization of parties. We study the primaries of Chile madeby the coalition of center-left (Concertation) to choose their candidates for mayor in 2012. We argue, first, forcing major electoral candidate incumbent, reduced turnout. Secondly, that the voter turnout in the general election was almost identical between communes where were and were not primary. Thirdly, that primaries improved eligibility mainly on the challengers. In consequence, the primaries did not stimulate turnout, but contributed to the success of the candidates.