5065 Background: Elevated levels of IL-6 in serum have been reported in patients (pts) with mullerian malignancies (MM) and have been associated with a poor prognosis. Little is know about the behavior of IL-6 during effective cytotoxic therapy and its correlation to various clinical parameters. Methods: Pts with surgically debulked FIGO Stage II, III, and IV MM were enrolled in the Modified Triple Doublets trial. 83 pts were assigned to a cohort in accordance with the extent of surgical debulking. Cohort I included women who had been optimally cytoreduced to <1cm of residual tumor. Cohort II consisted of pts who had either post-debulking residual disease >1cm or stage IV disease. Both cohorts were treated with 3 sequential chemotherapy doublets, gemcitabine/carboplatin, paclitaxel/carboplatin, and adriamycin/topotecan. Each doublet was delivered for 3 cycles. Serum was collected from pts prior to initiating each doublet at cycles 1, 4, 7 and at the end of study (post cycle 9). Serum IL-6 levels were measured in triplicate by sandwich ELISA. Results: Pts with MM had elevated levels of IL-6 following debulking surgery (mean = 12.7 pg/ml) as compared to normal controls (n = 11, mean IL-6 = 1.5 pg/ml, p =.01). While there was no significant correlation between IL-6 levels and stage of disease, the IL-6 serum concentrations did correlate with extent of surgical debulking (p = 0.0182). IL-6 concentrations dropped throughout all cycles of platinum based treatment with post platinum treatment mean concentration of 3.9pg/ml. IL-6 levels did not correlate with outcome of second look operation and there was no statistically significant correlation between IL-6 and CA-125 levels (p = 0.1612). Survival data is still immature with a median follow-up of 34 months, yet elevation of IL-6 levels following surgery demonstrates a trend towards inferior survival. Conclusions: IL-6 levels are elevated in ovarian cancer pts following surgical debulking and correlate with the volume of residual disease following surgical cytoreduction. Values decrease during cytoreductive platinum based chemotherapy although IL-6 was not as predictive of response as was CA-125. Data demonstrates a weak correlation betweenworse survival and elevated IL-6 levels. Supported by the Lana Vento Foundation. No significant financial relationships to disclose.