Suboptimal cytoreduction of advanced ovarian cancer is related to initial tumor bulk which correlates with CA125 level. Retrospective record study of 40 patients with stage III ovarian cancer. The ability of a CA125 threshold level of 500 U/mL to predict suboptimal cytoreduction was determined. Twenty-four (60%) of the patients were optimally cytoreduced. At the CA125 cut off level of 500 U/mL the sensitivity for predicting suboptimal debulking was 62% and specificity was 83%. Above a CA 125 level of 1500 U/mL none of the patients were optimally cytoreduced. More data are needed to determine the CA125 cut off level at which the standard approach of initial laparotomy and cytoreduction may be modified.