5109 Background: Postsurgical intraperitoneal (IP) platinum-based chemotherapy should be strongly considered for patients (pts) with optimally debulked advanced epithelial ovarian cancer (EOC) due to a demonstrate survival advantage. However, anecdotal experience indicated unexpected sites of recurrence after IP chemotherapy. We hypothesize that the distribution of first recurrences will differ between pts receiving adjuvant IP chemotherapy and IV chemotherapy. Methods: Pts with stage IIIC optimally debulked EOC diagnosed between 1/03 and 6/08 were divided into two groups based on type of adjuvant chemotherapy: IV or 4+ cycles IP. Clinical data including the site of first recurrence was collected from medical records. Recurrences were defined as pelvic, lower abdominal, upper abdominal, abdominal lymph nodes (LN), extra- abdominal LNs, and distant. The distribution of recurrences was compared between IV and IP groups using standard two-sided statistical tests. Results: Sixty of 104 pts (57.7%) in the IV group and 44 of 111 pts (39.6%) in the IP group met inclusion criteria and have recurred. In both groups, 60% of pts first recurred in multiple locations. More pts in the IV group had a first recurrence in the lower abdomen/pelvis than the IP group, but more pts in the IP group had a first recurrence in the upper abdomen and extra-abdominal LNs (see Table). Conclusions: The data suggest that pts receiving IP chemotherapy more often recur in both the upper abdomen and at sites outside of the abdominal cavity, while less likely to recur exclusively in the lower abdomen/pelvis. These findings may reflect the effectiveness of IP chemotherapy dwelling within the anatomic areas of peritoneal distribution. Sites of first recurrence in patients receiving IV versus IP chemotherapy for ovarian cancer Sites of first recurrence IP group N = 44 (%) IV group N = 60 (%) P Lower abdomen/pelvis 18 (40.9) 39 (65.0) 0.015 Upper abdomen 28 (63.6) 24 (40.0) 0.017 Abdominal LNs 15 (34.1) 24 (40.0) 0.54 Extra-abdominal LNs 15 (34.1) 7 (11.7) 0.006 Distant metastasis 10 (34.1) 7 (11.7) 0.13 Only lower abdomen/pelvis 6 (13.6) 22 (32.8) 0.009 Only extra-abdominal LNs or distant metastasis 4 (9.1) 1 (1.5) 0.080 No significant financial relationships to disclose.