Contrary to what an important part of the theory says, campaign expenditure has a significant effect on the electoral success of incumbents in the House of Representatives elections of 2005 in Chile. Moreover, electoral performance of expenditure is greater for those candidates with more than one period in office. Campaign expenditure not only adds to the "incumbency advantages" of incumbents, but multiplies their effect on electoral performance. Secondly, it is assessed that incumbents who won in 2001 by greater margins in their coalition tend to show greater campaign expenditures (contrary to what was expected). On one hand, this fact is coherent with the idea that candidates tend to perceive that their expenses multiply their qualities and do not present diminishing returns. This behavior is also reinforced by rationale of the public campaign financing, which reimburses money according to votes attained and makes, as theory suggests that the decision to spend be influenced by the expectations of getting a greater subsidy.