To investigate the applications and effects of neuromuscular electrical stimulation (NMES) in critically ill patients in ICU by means of a systematic review.Electronic searches were conducted in the databases Medline, CINAHL, Cochrane Central Register of Controlled Trials, Web of Science, Embase, ProQuest Health and Medical Complete, AMED, and PEDro. The PEDro score was used to assess the methodological quality of the eligible studies.The search yielded a total of 9759 titles and nine articles satisfied the eligibility criteria. These studies showed that NMES can maintain or increase muscle mass, strength and volume, reduce time in mechanical ventilation and weaning time, and increase muscle degradation in critically ill patients in ICU. Two studies allowed a meta-analysis of the effects of NMES on quadriceps femoris strength and it showed a significant effect in favor of NMES in the Medical Research Council (MRC) Scale (standardized mean difference 0.77 points; p=0.02; 95% CI: 0.13-1.40).The selected studies showed that NMES has good results when used for the maintenance of muscle mass and strength in critically ill patients in ICU. Future studies with high methodological quality should be conducted to provide more evidence for the use of NMES in an ICU setting.