Rationale and Objectives:The purpose of this study was to compare the accuracy of MDCT and lapa-roscopy in the prediction of peritoneal carcinomatosis index score. Reproducibility of MDCT interpreta-tion was also assessed.Methods:This prospective study included 85 ovarian cancer patients underwent MDCT and diagnosticlaparoscopy before cytoreductive surgery. We calculated the accuracy of diagnostic modalities in thecalculation of the peritoneal cancer index score (PCI). Radiologist interobserver agreement was calcu-lated using kappa statistics.Results:Nine hundred-thirty (84.2%) of the 1105 regions had peritoneal deposits at exploratory laparot-omy. Computed tomography (CT) and laparoscopy sensitivity were 94.9%, 98.3%, specificity 86.7%,80.4%, PPV 97.9 %, 96.8%, NPV 72.2%, 88.8 %, and accuracy 93.8 %, 95.7%, respectively. However,computed tomography (CT) diagnostic performance is less accurate than laparoscopy in pelvic andsmall intestinal regions; no statistically significant differences were evident regarding total PCI scorecompared to surgery (p>0.05). CT and laparoscopy correctly depicted peritoneal carcinomatosis in88.2%, 90.6% of patients, respectively. Optimal cytoreduction was achieved in 68 (80%) patients.Conclusion:Both CT and laparoscopy seems to be effective tools for assessment of peritoneal carci-nomatosis using the PCI score. Dedicated MDCT protocol with routine use of a standardized PCI formmay provide better comprehensive multi-regional analysis that may help surgeons referring patients tothe best treatment option. Laparoscopy is a valuable tool in cases with a high risk of suboptimal cytore-duction related to disease extent.