Background: Randomized, phase III trial to evaluate safety and efficacy of topotecan and carboplatin (TC) compared with standard platinum-based combinations in platinum-sensitive recurrent ovarian cancer (ROC). Patients and methods: Patients were randomly assigned in a 1:1 ratio to the experimental TC arm (topotecan 0.75 mg/m2/days 1-3 and carboplatin AUC 5 on day 3 every 3 weeks) or to one of the standard regimes [(PC) paclitaxel plus carboplatin; (GC) gemcitabine plus carboplatin; (PLDC) pegylated liposomal doxorubicin and carboplatin] which could be chosen by individual preference but before randomization. The primary end point was progression-free survival (PFS) after 12 months. Overall survival (OS), response rate, toxicity, quality of life and treatment preference regarding standard treatment were defined as secondary end points. Results: A total of 550 patients were recruited. The PFS rate after 12 months was 37.0% for TC compared with 40.2% in the standard combinations (P = 0.470). The overall response rate was 73.1% for TC versus 75.1% for standard combinations (P = 0.149). After a median follow-up of 20 months, the median PFS was 10 months [95% confidence interval (CI) 9.4-10.6] and did not differ between both arms (P = 0.414). The median OS was 25 months in the TC arm versus 31 months in the standard arm (95% CI: 22.4-27.6 resp. 26.0-36.0; P = 0.163). Severe hematologic toxicities (grade 3/4) were rare in the experimental arm (P < 0.001), with 17.4% leucopenia, 27.8% neutropenia and 15.9% thrombopenia. Conclusion: The combination of carboplatin and topotecan was well tolerated with significant lower rates of severe hematological toxicities but did not improve PFS or OS in platinum-sensitive relapsed ovarian cancer compared with established standard regimens.