ObjectiveTo evaluate the efficacy and safety of midazolam in the prevention of etomidate-induced myoclonus. MethodsDatabases including PubMed, EMbase, The Cochrane Library (Issue 8, 2015), CBM, WanFang Data, VIP, and CNKI were electronically searched to collect randomized controlled trials (RCTs) about midazolam in the prevention of etomidate-induced myoclonus from inception to August, 2015. Two reviewers independently screened literature, extracted data and assessed the risk of bias of included studies. Then, meta-analysis was performed by RevMan 5.2 and Stata 12.0 softwares. ResultsA total of 14 RCTs involving 1 274 patients were included. The results of metaanalysis showed that, compared with placebo, pretreatment with midazolam injection could reduce the incidence of myoclonus (RR=0.28, 95%CI 0.19 to 0.42, P<0.000 01). The sub-group analysis based on different doses of midazolam showed that all three different doses of midazolam (0.015 mg/kg, 0.03 mg/kg and 0.05-0.1 mg/kg) could reduce the incidence of myoclonus effectively (all P values <0.05). ConclusionPretreatment with midazolam injection can reduce the incidence of etomidate-induced myoclonus without increasing the risk of recovery latency and over sedation. Due to the limited quality of included studies, the above conclusion needs to be further verified by more high quality studies.