Although preliminary results suggest that allogeneic hematopoietic stem cell transplantation (allo HCT) for ovarian cancer (OC) is a feasible procedure, the low patient number in previous studies had limited ability to evaluate the true benefit of allo HCT in OC. This retrospective multicenter study included 30 patients with OC allografted between 1995 and 2005 to determine the outcome of patients with OC treated with allo HCT. Prior to allo HCT, patients were in complete response (n = 1), partial response (n = 7), stable disease (n = 11) or had progressive disease (n = 13). An objective response (OR) was observed in 50% (95% CI, 33-67) of patients. Three patients of responding patients had an objective response following the development of acute graft-versus-host disease (aGvHD). The cumulative incidence of chronic GvHD (cGVHD) was 34% (95% CI, 18-50). Transplant relative mortality rates were 7 and 20% on day 100 and 1 year, respectively. With a median follow-up of 74.5 months (range 16-148), median progression free survival (PFS) was 6 months and median overall survival (OS) was 10.4 months. Patients who developed cGvHD following allo HCT had a significant OS improvement compared to those who did not (17.6 months vs. 6.5 months, p = 0.042). However, PFS was not similarly significantly improved in patients who developed cGvHD (12 months versus 3.7 months, p = 0.81). Allo HCT in OC may lead to graft-versus-OC effects. Their clinical relevance remains to be shown.