OBJECTIVE To estimate the influence of gynecologic oncologists on the treatment and outcome of patients with ovarian cancer. METHODS Data were obtained from California Cancer Registry from 1994 to 1996. Kaplan-Meier and Cox proportional hazard methods were used for analyses. RESULTS Of 1,491 patients, the median age was 65 years (range: 13-100). Only 34.1% received care by gynecologic oncologists (group A) while 65.9% were treated by others (group B). Women in group A were more affluent (P<.001), were more educated (P=.036), were classified as white-collar employees (P=.128), and lived in urban regions (P<.001) compared with group B. Patients who saw gynecologic oncologists were more likely to have surgery as their initial treatment (91.9% versus 69.1%; P<.001), present with advanced (stage III-IV) cancers (78.2% versus 70.5%; P<.001), have more grade 3 tumors (61.7% versus 39.9%; P=.048), and receive chemotherapy (90.0% versus 70.1%; P<.001). Women in group B had a fourfold higher risk of having unstaged cancers (8.0% versus 2.1%; P<.001). The 5-year disease-specific survival of group A patients was 38.6% compared with 30.3% in group B (P<.001). On multivariable analysis, early stage, lower grade, and treatment by gynecologic oncologists were independent prognostic factors for improved survival. After adjusting for surgery and chemotherapy, there was no improvement in survival associated with care by gynecologic oncologists (hazard ratio=0.90, 95% confidence interval 0.78-1.03; P=.133). CONCLUSIONS In this study of 1,491 women, those who were treated by gynecologic oncologists were more likely to undergo primary staging surgery and receive chemotherapy. Stage, grade of disease, and treatment by gynecologic oncologists were important prognosticators.