The mainstay of treatment for advanced ovarian cancer is the multimodality approach of debulking surgery and paclitaxel--platinum chemotherapy. The size of residual lesions after primary surgery remains the most important prognostic factor for survival. Optimal primary debulking surgery can be performed in approximately 40% of patients and up to 80% if it is done by gynecologic oncologists, but sometimes at the cost of considerable morbidity and even mortality. Based on a trial conducted by the European Organization for Research and Treatment of Cancer, optimal as well as suboptimal interval debulking surgery increases overall (P=0.0032) and progression-free survival (P=0.0055). However, not all patients who have undergone suboptimal primary debulking surgery seem to benefit from interval debulking surgery. Preliminary data from the Gynecologic Oncology Group interval debulking study (GOG-152) indicate that, if the gynecologic oncologist makes a maximal effort to resect the tumor, patients who have undergone suboptimal debulking surgery probably gain little benefit from interval debulking surgery.