We report three patients with relapsed ovarian cancer who developed femoral head necrosis requiring endoprosthetic hip surgery 16-35 months after high-dose chemotherapy (HDC) with treosulfan (47 and 56 g/m(2) body-surface area (BSA)) given as 3-25 h infusions and followed by autologous peripheral blood stem cell (PBSC) transplantation. One woman received two courses of single agent treosulfan while the other two patients received one course of high-dose treosulfan either preceded or followed by high-dose carboplatin, etoposide and cyclophosphamide. A total of 30 women with ovarian cancer were treated with HDC at our unit and 21 of them received treosulfan-containing regimens. Femoral head necrosis was not observed in patients either receiving conditioning regimens without treosulfan (n=9) or when the total treosulfan dose was given over 3 consecutive days (n=3) or in patients with a diagnosis other than ovarian cancer and treated with high-dose treosulfan (n=10). We conclude that women with relapsed ovarian cancer receiving HDC with excessive single-dose treosulfan might be at an increased risk of developing bone necrosis.