OBJECTIVE: Guidelines for referring women with pelvic masses suspicious for ovarian cancers to gynecologic oncologists have been published jointly by Society of Gynecologic Oncologists (SGO) and the American College of Obstetricians and Gynecologists (ACOG). They are based on patient age, CA 125 level, physical findings, imaging study results, and family history. Although the guidelines are evidence-based, their predictive value in distinguishing cancers from benign masses is unknown. METHODS: Chart review for factors included in the guidelines of surgically evaluated women with pelvic masses at 7 tertiary care centers during a 12-month interval was performed. This information was used to estimate the predictive values of the SGO and ACOG guidelines in identifying patients with malignant pelvic masses. RESULTS: A total of 1,035 patients were identified, including 318 (30.7%) with primary malignancies of the ovary, fallopian tube, or peritoneum. Seventy-seven were younger than 50 years old (premenopausal group), and 240 were 50 years old or older (postmenopausal group). Fifty additional patients (4.8%) had cancers metastatic to the ovaries, and the remaining 667 (64.4%) had benign masses. The referral guidelines captured 70% of the ovarian cancers in the premenopausal group and 94% of the ovarian cancers in the postmenopausal group. The positive predictive value was 33.8% for the premenopausal group and 59.5% for the postmenopausal group, whereas the negative predictive values were more than 90% for both groups. Elevated CA 125 level was the single best predictor of malignancy in both groups. CONCLUSION: The SGO and ACOG referral guidelines effectively separate women with pelvic masses into 2 risk categories for malignancy. This distinction permits a rational approach for referring high-risk patients to a gynecologic oncologist for management. © 2005 by The American College of Obstetricians and Gynecologists.