e15508 Background: Neoadjuvant chemotherapy, compared to primary surgery, may be associated with less morbidity and comparable survival in a subset of ovarian cancer patients. There is no paradigm for selecting primary surgery versus neoadjuvant chemotherapy. The optimal duration of chemotherapy prior to interval surgery is also unknown. The purpose of this study is to develop a non-debulkability score (NDS). Methods: We identified 102 consecutive institutional cases of women with stage IIIC-IV ovarian cancer undergoing surgical management during the past 5 years. CT scans were reviewed for pleural effusions, ascites, studding, diaphragmatic, mesenteric, peri-splenic (PS), peri-hepatic and peri-colonic disease and retroperitoneal lymphadenopathy. Multivariate assessment of preoperative factors was carried out using backward stepwise regression (sig = p < 0.05). Results: 77 patients underwent initial surgery and 25 patients were treated with chemotherapy followed by surgery. 71 of 102 (70%) patients were optimally cytoreduced (residual disease \h = 1 cm). 27% of patients had microscopic residual disease (RD), 44% had between 0-1 cm, 5% had between 1-2 cm and 24% of patients had > 2 cm of RD. High CA-125 level (p \h 0.03), low albumin (p \h 0.03), high platelets (p \h 0.05) and para-aortic lymphadenopathy (PaL) (p \h 0.005) were predictive of RD. Low albumin (p \h 0.03), PS (p \h 0.001) and PaL (p \h 0.04) were predictive of a major surgical complication (COMP = organ injury, reoperation, death). NDS (0-70) was determined by adding 10 points each for CA-125 level > 500, platelets > 500K, PS and 20 points each for albumin \h 2.7, PaL. Mean NDS of patients who had successful surgery (optimal cytoreduction and no COMP) was significantly lower compared to patients who had unsuccessful surgery (suboptimal cytoreduction or COMP) (11 ± 2 versus 37 ± 3; p \h 0.0001). The sensitivity, specificity, PPV and NPV of NDS were 85%, 88%, 93% and 73%; respectively. Conclusions: CA-125, albumin, platelets, PS and PaL predicted successful surgery. NDS may be useful in selecting initial treatment in advanced ovarian cancer patients. For patients receiving neoadjuvant chemotherapy, NDS might further help guide optimal timing of interval surgery. No significant financial relationships to disclose.