BACKGROUND Interval debulking surgery (IDS), following induction or neoadjuvant chemotherapy, may have a role in treating advanced epithelial ovarian cancer (stage III to IV) where primary debulking surgery is not an option. OBJECTIVE To assess the effectiveness and complications of IDS for women with advanced stage epithelial ovarian cancer. METHODS We searched the Cochrane Gynaecological Cancer Group's Specialised Register to June 2012, the Cochrane Central Register of Controlled Trials (CENTRAL) 2012, Issue 6, MEDLINE to June 2012 and EMBASE to June 2012. METHODS Randomised controlled trials (RCTs) comparing survival of women with advanced epithelial ovarian cancer, who had IDS performed between cycles of chemotherapy after primary surgery with survival of women who had conventional treatment (primary debulking surgery and adjuvant chemotherapy). METHODS Two review authors independently assessed trial quality and extracted data. Searches for additional information from study authors were attempted. We performed meta-analysis of overall and progression-free survival (PFS), using random-effects models. RESULTS Three RCTs randomising 853 women, of whom 781 were evaluated, met the inclusion criteria. Meta-analysis of three trials for overall survival (OS) found no statistically significant difference between IDS and chemotherapy alone (hazard ratio (HR) = 0.80, 95% confidence interval (CI) 0.61 to 1.06, I² = 58%). Subgroup analysis for OS in two trials, where the primary surgery was not performed by gynaecologic oncologists or was less extensive, showed a benefit of IDS (HR = 0.68, 95% CI 0.53 to 0.87, I² = 0%). Meta-analysis of two trials for PFS found no statistically significant difference between IDS and chemotherapy alone (HR = 0.88, 95% CI 0.57 to 1.33, I² = 83%). Rates of toxic reactions to chemotherapy were similar in both arms (risk ratio = 1.19, 95% CI 0.53 to 2.66, I² = 0%), but little information was available for other adverse events or quality or life (QoL). CONCLUSIONS We found no conclusive evidence to determine whether IDS between cycles of chemotherapy would improve or decrease the survival rates of women with advanced ovarian cancer, compared with conventional treatment of primary surgery followed by adjuvant chemotherapy. IDS appeared to yield benefit only in women whose primary surgery was not performed by gynaecologic oncologists or was less extensive. Data on QoL and adverse events were inconclusive.