Objective To evaluate the efficacy and safety of intravitreal bevacizumab (IVB) as a preoperative adjunct to vitrectomy for prevention of postoperative vitreous hemorrhage (VH) in proliferative diabetic retinopathy (PDR) patients.Methods This was a meta analysis of randomized controlled trials (RCT). A computerized search was conducted in the Medline, Embase, Cochrane Library, Chinese Biomedical Database and Chinese Journal Full text Database combined with manually searching of bibliographies of pertinent articles, journals and literature reference proceedings. RCT on IVB as a preoperative adjunct to vitrectomy for prevention of postoperative VH in PDR were selected according to inclusion and exclusion criteria. After the data extraction, methodological quality assessment of RCT that were included using the Jadad scale. The outcome measures included the incidence of postoperative VH, postoperative best corrected visual acuity (BCVA), the incidence of postoperative retinal reattachment and postoperative complications. The statistical analysis was performed by Stata/SE 11.2. The weighted mean difference (WMD) with 95% confidence interval (CI) was calculated for continuous variable, and odds ratio (OR) with 95% CI for dichotomous variable. Results In total, seven RCT that fulfilled the eligibility criteria were included in the metaanalysis involving 170 patients in IVB group and 161 patients in control group. According to the Jadad scale, one RCT scored 5 points, one RCT scored 3 points and the other 5 RCT scored 1 point. The results suggested that IVB group achieved lower incidence of postoperative VH than control group both within four weeks after surgery (OR=3.28, 95% CI: 1.58-6.82,P=0.00), and over four weeks after surgery (OR=2.51, 95% CI1.21-5.22,P=0.01). There was no significant differences in incidence of postoperative VH between IVB and control group either at postoperative 3 months (OR=2.52, 95% CI: 0.74-8.57,P=0.14), or at postoperative 6 months (OR=3.26, 95% CI: 0.50-21.45,P=0.22). The results suggested that IVB group achieved better postoperative BCVA than control group (WM1=0.29, 95% CI: 0.13-0.44,P=0.00), but no significant differences were found between IVB and control group on the incidence of postoperative retinal reattachment (OR=0.39, 95% CI:0.10ndash;1.59,P=0.19), postoperative retinal re-detachment (OR=2.36, 95% CI: 0.74- 7.56, P=0.15) and postoperative neovascular glaucoma (OR=1.47, 95% CI: 0.28ndash;7.71,P=0.65). Conclusions IVB as a preoperative adjunct to vitrectomy could prevent postoperative VH in PDR effectively, and be relatively safe. However, a high-quality, multicenter, large sample, long-term RCT is warranted to be further investigated.