Complicated UTIs (cUTIs) are one of the leading causes of the gram negative bacteraemia which occur in patients who have a functionally, metabolically, or anatomically abnormal urinary tract. The primary objective of this study was to compare efficacy of Piperacillin/Tazobactam (PT) and Cefoperazone/Sulbactam (CPS) combinations in complicated Urinary Tract Infections. At entry, total 92 patients admitted in the hospital due to cUTI were enrolled. Among of 92 patients, 49 patients were given PT while 43 patients were given CPS combinations. Clinical symptoms were registered and scored as mild (1) moderate (2) or severe (3). The follow-up were done daily till the patient is discharged. Thereafter, one follow up visit was done within 4 to 9 days of after discharge, termed as test of cure (TOC). Furthermore, one late follow up visit after 6 to 8 weeks was done, known as late follow up visit (LFU). Clinical assessments and microbiological analysis were done at the time of TOC and LFU. The mean baseline clinical score for PT and CPS were 10.89 ± 2.23 and 10.28 ± 2.33, respectively. At TOC visit, PT and CPS groups, clinical scores were 0.86 + 2.35 and 1.36 ± 3.48, respectively; suggesting significant improvement from baseline (p< 0.001). Rate of clinical improvement at TOC visit was 92.68% and 87.50%, while microbiological cure rate was 87.80% and 93.75% with PT and CPS groups respectively. While, at LFU visit, clinical scores in PT and CPS groups were 1.32 + 3.37 and 1.65 + 3.56, respectively, suggesting significant improvement from baseline (p < 0.001). Clinical cure rate at LFU visit was 87.80% and 87.75% while microbiological cure rate at LFU visit was 82.92 and 77.00% in PT and CPS groups, respectively. These results suggest that both regimens have no significant difference for the treatment of cUTI. PT and CPS, both the combinations, are equally efficacious in treatment of cUTI.