Objective. To determine the safety and efficacy of a novel illudin S derivative, irofulven(MGI- 114), in patients with recurrent ovarian cancer who had received extensive prior chemotherapy. Methods. The trial was an open label phase II study. Patients initially enrolled in this study were treated every 14 days with a dose of 24 mg/m2. Unexpected retinal toxicity associated with this dose and schedule lead to modification of the dosing to 0.55 mg/kg on the same schedule with a maximum individual dose of 50 mg. Dose reductions were permitted based on both hematologic and non- hematologic toxicities. Results. Seventy- four women were accrued and stratified into two cohorts including 58 women with platinum- resistant disease and 16 with platinum- sensitive disease. Non- hematologic toxicities included nausea, vomiting, and fatigue. Thirty- one women had between one and six visual symptoms, most were Grade 1 and 2 in nature. The majority of visual toxicities resolved either during treatment or post- treatment with irofulven. There was one partial response in each cohort with 19 (33% ) and 8 (50% ) of women having stable disease in the platinum- resistant and platinum- sensitive cohorts, respectively. Conclusions. Irofulven at 24 mg/m2 on every 14- day schedule is associated with significant retinal toxicity in this patient population. Dosing at 0.55 mg/kg has persistent retinal toxicity, yet demonstrated only limited anti- tumor activity in a population of women who had received extensive prior chemotherapy. Objective. To determine the safety and efficacy of a novel illudin S derivative, irofulven (MGI-114), in patients with recurrent ovarian cancer who had received extensive prior chemotherapy. Methods. The trial was an open label phase II study. Patients initially enrolled in this study were treated every 14 days with a dose of 24 mg / m2. Unexpected retinal toxicity associated with this dose and schedule lead to modification of the dosing to 0.55 mg / kg on the same schedule with a maximum individual dose of 50 mg. Dose reductions were permitted based on both hematologic and non-hematologic toxicities. Results. Seventy- four women were accrued and stratified into two cohorts including 58 women with platinum- resistant disease and 16 with platinum- sensitive disease. Non- hematologic toxicities included nausea, vomiting, and fatigue. Thirty- one women had between one and six visual symptoms, most were Grade 1 and 2 in nature. The majority of visual toxicities resolved either during treatmen There was one partial response in each cohort with 19 (33%) and 8 (50%) of women with stable disease in the platinum- resistant and platinum- sensitive cohorts, respectively. Conclusions. Irofulven at 24 mg / m2 on every 14-day schedule is associated with significant retinal toxicity in this patient population. Dosing at 0.55 mg / kg has persistent retinal toxicity, yet demonstrated only limited anti- tumor activity in a population of women who had received extensive prior chemotherapy.