Background: Combinations of a third-generation cephalosporin and metronidazole, with or without an aminoglycoside, often are used for the treatment of intra-abdominal infections in surgical settings. Simpler regimens that preserve an adequate spectrum of coverage, but allow easier administration and have fewer side effects, may be a more desirable option. Methods: This randomized, open-label, active comparator study evaluated the effectiveness (non-inferiority hypothesis) of the beta-lactam/beta-lactamase inhibitor combination cefoperazone-sulbactam (2-8 g/day), compared with ceftazidime (2-6 g/day)-amikacin (15 mg/kg/day)-metronidazole (500 mg three times daily) in 154 and 152 subjects, respectively, having intra-abdominal infections. The study was conducted at 17 centers in India. Results: Non-inferiority of cefoperazone-sulbactam (91.9%) compared with ceftazidime-amikacin-metronidazole (81.8%) was demonstrated for continued resolution of clinical signs and symptoms at the 30-day follow-up (primary endpoint) with a treatment difference of 10.1% (95% confidence interval 2.1%, 18.1%; pre-defined non-inferiority limit > -12.5%). Superiority of cefoperazone-sulbactam also was demonstrated for this endpoint, with significantly more subjects achieving continued resolution at the 30-day follow-up than in the comparator group (p = 0.015). On microbiologic outcomes, cefoperazone-sulbactam had higher success rates than ceftazidime-amikacin-metronidazole (92.9% vs. 80.0%). The pathogens (202 isolated) isolated most commonly were Escherichia coli (38.6%) and Klebsiella spp. (12.9%). The incidence of treatment-related adverse events was 6.5% and 16.4% in the cefoperazone-sulbactam and ceftazidime-amikacin-metronidazole groups, respectively, with more discontinuations due to treatment-related adverse events in the comparator arm (3.2% vs. 9.9%). Conclusion: Empirical cefoperazone-sulbactam monotherapy could be a useful adjunct to surgical intervention for intra-abdominal infections.