OBJECTIVE The aim of this study is to evaluate the results of neoadjuvant chemotherapy (NACT) and the impact of interval debulking surgery (IDS) on clinical outcomes of patients with advanced-stage ovarian cancer. METHODS We performed a retrospective analysis on 92 patients with advanced ovarian cancer admitted to Vali-Asr Gynecologic oncology departments during 1996-2002. Comparison was made with results of neoadjuvant chemotherapy of 24 patients with unresectable advanced epithelial ovarian cancer treated with platinum- based NACT followed by IDS and clinical outcomes of 68 consecutive stage III and IV ovarian cancer patients treated with primary cytoreduction followed by platinum-based adjuvant chemotherapy. RESULTS Primary cytoreductive surgery caused longer survival compared to neoadjuvant chemotherapy. Patients who underwent optimal interval debulking surgery (IDS) had a better progression free survival (PFS) (p=0.002) and overall survival (p=0.03) than those who did not. There were not significant differences between the two groups in complications of surgery. CONCLUSIONS NACT followed by successful IDS can lead to high survival percentage in patients with chemoresponsive advanced ovarian cancer; although the result is more effective in those with optimal primary cytoreduction, we still got the same results with those with suboptimal primary cytoreduction.