Levosimendan is an inotropic agent that has been shown in small studies to treat low cardiac output syndrome in cardiac surgery. However, large randomised controlled trials (RCTs) have been recently published and presented neutral results. We sought to determine the effect of levosimendan on mortality in adults with low ejection fraction undergoing cardiac surgery. We searched different databases: Medline, Embase, Cochrane Central Register of Controlled Trials, and clinical trial registries. We included RCTs comparing events in the levosimendan versus placebo in adult patients with ejection fraction ≤ 35% undergoing cardiac surgery. Outcomes were mortality at 30-day, mortality beyond 30−day, acute kidney injury and myocardial infarction. Five trials with a total of 1519 patients were selected. Four trials were rated as low risk of bias. Our meta-analysis showed no significant difference between levosimendan versus placebo mortality at 30-day [odds radio (OR): 0.62; 95% confidence intervals (CI): 0.32 to 1.20; I² = 33%; high quality evidence] and mortality beyond 30-day (OR: 0.71; 95% CI: 0.46 to 1.11; I² = 0%). Similarly, there were no significant differences between the levosimendan versus placebo in the incidence of acute kidney injury (OR: 0.61, 95% CI: 0.33−1.13) and myocardial infarction (OR: 0.41, 95% CI: 0.08 to 1.22). The current evidence suggests that levosimendan is not associated with significantly reduced mortality in patients with reduced ejection fraction undergoing cardiac surgery.