ObjectiveTo systematically review the effects of ulinastatin on postoperative intensive care unit (ICU) stay time and mechanical ventilation time in patients with cardiopulmonary bypass (CPB). MethodsWe searched databases including MEDLINE, EMbase, Web of Science, The Cochrane Library (Issue 5, 2014), CBM, CNKI, WanFang Data and VIP from inception to May, 2014, to collect randomized controlled trials (RCTs) of ulinastatin for patients with CPB. Meanwhile, conference papers, dissertation and references of included studies were also retrieved manually to collect additional studies. Two reviewers independently screened literature, extracted data and assessed the risk of bias of included studies. Then, meta-analysis was performed using RevMan 5.2.0 software. ResultsA total of 7 RCTs involving 299 patients were included. The results of meta-analysis showed that:(1) There was no difference between two groups in ICU stay time (MD=-5.40, 95%CI -17.75 to 6.94, P=0.39); (2) The time of mechanical ventilation of the urinastatin group was significantly shorter than that of the saline group (MD=-6.58, 95%CI -10.61 to -2.56, P=0.000 1). The results of subgroup analysis showed that:in the CPB time >100 min subgroup, the time of mechanical ventilation of the urinastatin group was significantly shorter than that of the saline group (MD=-13.85, 95%CI -21.28 to -6.42, P=0.000 3); however, in the CPB time <100 min subgroup, there was no significant difference between two groups in the time of mechanical ventilation (MD=-1.39, 95%CI -3.22 to 0.45, P=0.14). ConclusionCurrent evidence shows, compared with saline, the administration of urinastatin during CPB can reduce postoperative mechanical ventilation time, but cannot reduce ICU stay time. Due to limited quality and quantity of the included studies, more high quality studies are needed to verify the above conclusion.