Prognostic outcome of patients with bulky disease after primary surgery in ovarian cancer remains extremely poor. One possible approach to achieve prolonged survival is secondary debulking surgery, but only in those patients without residual tumor after the second surgery. In 79 patients with secondary debulking surgery preoperative CA125 values were determined. In 52% of the patients with CA125 values below 35 U/ml a tumor free situation could be achieved at secondary debulking. In contrast, the percentage of patients macroscopically free of disease with levels above 35 U/ml was only 22%. Furthermore, there was a significant difference in survival time depending on CA125 values at the time of secondary debulking. Patients with levels below 35 U/ml survived 49 months, women with values above 35 U/ml survived only 30 months respectively. In conclusion, CA125 is an important prognostic tool for predicting a tumor free situation at secondary debulking surgery. In patients with values above 35 U/ml secondary debulking should be indicated restrictively, even if other preoperative diagnostic tools would predict a tumor free situation after secondary cytoreductive surgery.