This study examines the relationship between voter turnout in competitive authoritarian elections and the performance of opposition parties. Because the individuals most likely to abstain from voting in such elections are opponents to the regime, increases in voter turnout rates should be positively correlated with increases in opposition vote shares. Evidence from 61 competitive authoritarian elections in the post-Cold War era supports this expectation: higher voter turnout is associated with more votes for the opposition. This relationship holds under a variety of circumstances, even when taking into account differences in electoral misconduct from one competitive authoritarian election to the next. Data from recent state-level elections in Malaysia reveal a similar pattern. By showing that opposition parties tend to fare better when voter turnout rates are higher, this study contributes to our understanding of voting dynamics and opposition performance in non-democratic contexts.