Objective. The goal of treating recurrent ovarian cancer is disease control while minimizing toxicity. Fulvestrant, a novel estrogen receptor (ER) antagonist, has proven clinically beneficial and well-tolerated in treating recurrent breast cancer. Ovarian cancer often expresses ER and may respond to anti-estrogen therapy. We evaluated fulvestrant in women with recurrent ovarian or primary peritoneal cancer. Methods. Patients with ER-positive, multiply recurrent ovarian or primary peritoneal carcinoma and either measurable disease according to RECIST criteria or an abnormal and rising CA-125 were eligible for enrollment. Treatment consisted of single agent fulvestrant, 500 mg IM on Day 1, 250 mg IM on Day 15, and 250 mg IM on Day 29 and every 28 days thereafter until either intolerance or disease progression. Disease response was assessed by monthly physical exams and CA-125 levels as well as CT scans bimonthly. The primary endpoint was clinical benefit (CB=complete response (CR)+partial response (PR)+stable disease (SD)) at 90 days. Results. Thirty-one women were enrolled and 26 women (median age of 61) met inclusion criteria and received at least one dose. Patients had received a median of 5 prior chemotherapeutic regimens (range: 2-13). We observed one CR (4%), one PR (4%), and 9 patients with SD (35%) using modified-Rustin criteria (CA-125 level). Using modified-RECIST criteria 13 patients (50%) achieved SD. The median time to disease progression was 62 days (mean 86 days). Grade 1 toxicity included headache (1 patient) and bromidrosis (2 patients). Conclusions. Fulvestrant is well-tolerated and efficacious. Objective response rates are low, but disease stabilization was common.