Objective: To determine the indications, patterns of practice, and complication rates for prophylactic oophorectomy in Ontario. Methods: From hospital discharge abstracts, 82 hospitals were identified where at least one patient had a prophylactic oophorectomy since 1992. Ethics approval for the chart review was obtained from 41 hospitals (50%), was denied at 10 (12%) and is pending at 31 facilities. Using the International Classification of Disease diagnostic code for family history of ovarian cancer (V16.4) and prophylactic oophorectomy (V50.42), the medical records departments were asked to retrieve the charts. One abstractor reviewed the charts using a standard form to collect demographic information, indications for surgery, details of surgery and complications. Results: From 1992-1998, 263 women underwent PO in 41 hospitals. A BRCA1 or BRCA2 mutation was recorded in 16 cases. Thirty-six patients had a past history of breast cancer. In 127 women, a family history was the sole reason for surgery; the remaining 136 women had a coexisting gynecologic complaint. Laparotomy was used exclusively in 155 cases, laparoscopy in 79 and vaginal access in 12 cases. Seventeen women required conversion to laparotomy during the operation. The mean length of hospital stay was 3.7 days (0-14 days). Thirty-six women (14%) had complications. Conclusion: We have described the indications for surgery, trends in surgical practice and surgical complications for women receiving prophylactic oophorectomy in Ontario. Prior to prophylactic oophorectomy, the indications and benefits should be clear to both patient and physician. Optimally, all women should receive genetic counseling to help define risk for ovarian and breast cancer, medical and surgical options, impact of oophorectomy on cancer risk, risk of surgical complications, and the consequences and management of surgical menopause.