Ｏｂｊｅｃｔｉｖｅ　To evaluate the effects of single-dose etomidate on the mortality and the risk of adrenal insufficiency in patients with critical illness.　Methods　PubMed, EMBASE, Medline, Web of Science, the Cochrane Library, CNKI, Wanfang Database, and Vip Database were searched for the relevant randomized controlled clinical trials and observational studies. According to the inclusion and exclusion criteria, two researchers independently selected the literature, extracted the data, and then performed Meta-analysis usinge RevMan5.3 software. The Mantel-Haenszel method with the random-effects modeling was used to calculate pooled relative risks (RR) and 95%CI.　Results　Twenty-six studies ［5 randomized controlled trial(RCT) and 21 observational studies］ involving 7 430 patients were qualified. Pooled analysis suggested that etomidate was not associated with increased mortality in critical patients ［RCT:RR=1.16, 95%CI(0.93, 1.45), P＞0.05］ ［observational studies:RR=1.07, 95%CI(1.00, 1.14)(P=0.05)］. These findings were also consistent across all subgroup analyses off observational studies. Etomidate increased the risk of adrenal insufficiency in critical patients［RCT:RR=1.61, 95%CI(1.06, 2.46)(P＜0.01)］ ［observational studies:RR=1.41, 95%CI(1.22, 1.62)(P＜0.01)］.　Conclusions　Current evidence indicates that single-dose etomidate does not increase the mortality， but increases the risk of adrenal insufficiency in critical patients. However, this finding largely relies on data from observational studies and is potentially subject to selection bias. Therefore, high-quality and adequately powered RCT are warranted.