Abstract: OBJECTIVE To quantify the risk of bevacizumab-related adverse effects in patients with metastatic colorectal cancer (mCRC). METHODS Randomized controlled clinical trials (RCTs) of bevacizumab plus chemotherapeutic agents for patients with mCRC from the databases of Cochrane Library, Pubmed, EMBASE, CNKI, CBM and Wanfang Database for investigating side effects were retrieved. Then the methodological quality of included studies were evaluated. Meta-analysis was performed with the Review Manager 5.1. RESULTS It was retrieved seven out of 198 eligible papers encompassing 3 493 patients. The relative risk of hypertension (RR=3.93, P<0.001), gastrointestinal perforations (RR=4.10, P=0.02), proteinuria (RR=3.76, P=0.009), thrombosis events (RR=1.33, P=0.008) and bleeding (RR=1.94, P=0.010) were significantly increased in the bevacizumab group. There was no statistical difference in pulmonary embolism (RR=0.78, 95% CI 0.42-1.46, P=0.44), leukopenia (RR=1.15, 95% CI 0.95-1.40, P=0.14), grade 3-4 diarrheas (RR=1.17, 95% CI 0.98-1.40, P=0.09) between both groups. The grade 3-4 adverse events slightly increased in the bevacizumab group (RR=1.16, 95% CI 1.09-1.24, P<0.001). There was no statistical difference in fatal adverse events between both groups. CONCLUSION These results show that the risks of hypertension, gastrointestinal perforations, thrombosis, proteinuria and bleeding of bevacizumab group were higher than the chemotherapy alone group. However, bevacizumab did not increase the incidence of fatal adverse events compared with chemotherapy alone.