Epithelial ovarian cancer is usually diagnosed at an advanced stage with a bulky tumor in the pelvis and upper abdomen. The most common therapeutic strategy begins by a surgical operation that allows histologic diagnosis, accurate staging and maximal debulking. Since the papers by Griffiths at the end of the seventies, the volume of the residual tumor after surgery appears to be one of the most important prognostic factors in all series. Indeed, patients whose tumor is completely or optimally debulked have greater chances of prolonged survival of about 50% at 5 years. Surgeons experienced in this field can achieve optimal debulking in about 75 to 80% of cases. But, in order to reach this objective, they must often perform an ultra-radical operation with extensive peritonectomies, lymphadenectomies and intestinal resections. Moreover, since 1983, Hacker has shown that the initial tumor bulk was still a poor prognostic factor even after debulking. Today it can be demonstrated that the greater the tumor bulk the more aggressive must be the surgical procedure in order to be optimal and the final benefit will nevertheless be proportionally lower with a higher morbidity rate. This paradigm leads the surgeons to currently try to more accurately assess the initial tumor bulk in order to determine wether the tumor would be optimally debulked by means of a well-standardised operation. If not, the alternative strategy would be 3 chemotherapy courses as front-line treatment before debulking surgery, which hopefully would be easier. Trials are needed in order to validate this strategy despite the fact that some patients will unfortunately have their prognosis jeopardized by the chemoresistance of their tumor.