Using variation in firms’ exposure to their CEOs resulting from hospitalization, we estimate the effect of chief executive officers (CEOs) on firm policies, holding firm-CEO matches constant. We document three main findings. First, CEOs have a significant effect on profitability and investment. Second, CEO effects are larger for younger CEOs, in growing and family-controlled firms, and in human-capital-intensive industries. Third, CEOs are unique: the hospitalization of other senior executives does not have similar effects on the performance. Overall, our findings demonstrate that CEOs are a key driver of firm performance, which suggests that CEO contingency plans are valuable.