Objective: The aim of this study was to assess the clinical efficacy and safety of ceftolozane-tazobactam in the treatment of complicated intra-abdominal infections (cIAIs) and complicated urinary tract infections (cUTIs) in adult patients through meta-analysis. Methods: PubMed, Embase and Cochrane databases were searched up to June 2019. Only randomized controlled trials (RCTs) that evaluated ceftolozane-tazobactam and comparators for treating cIAIs and cUTIs in adult patients were included. Primary outcome was clinical cure rate; secondary outcomes were clinical failure rate, microbiological eradication rate, and risk of an adverse event (AE). Results: Three RCTs were included. Overall, ceftolozane-tazobactam had a clinical cure rate similar to comparators in the microbiological intent-to-treat (mITT) population (odds ratio [OR], 0.87; 95% confidence interval [CI], 0.43-1.79; I-2 = 73%) and in the clinically evaluable (CE) population (OR, 1.22; 95% CI, 0.79-1.88; I-2 = 0%). Furthermore, ceftolozane-tazobactam had a similar microbiological eradication rate for pathogens (OR, 1.31; 95% CI, 0.42-4.10; I-2 = 37%). There were no significant differences in the risks of treatment-emergent AEs (OR, 1.04; 95% CI, 0.87-1.23; I-2 = 0%), serious AEs (OR, 1.16; 95% CI, 0.67-1.99; I-2 = 37%), discontinuation of study drug due to an AE (OR, 0.77; 95% CI, 0.17-3.47) and mortality (OR, 1.62; 95% CI, 0.69-3.77, I-2 = 0%) between ceftolozane-tazobactam and comparators. Conclusions: The clinical efficacy of ceftolozane-tazobactam is as high as that of comparators in the treatment of cIAIs and cUTIs in adult patients, and this antibiotic is well tolerated. (C) 2019 Published by Elsevier B.V.