Nevoid basal cell carcinoma syndrome, also known as Gorlin syndrome, is an autosomal dominant genetic disorder predisposing affected individuals to characteristic benign and malignant tumors involving the jaw (such as odontogenic keratocyst), skin, brain, ovaries, and heart. Additionally, skeletal malformations and other abnormalities may also be present. Ovarian fibromas are the common neoplasm in the gynecologic tract associated with Nevoid basal cell carcinoma syndrome. Nevoid basal cell carcinoma syndrome–associated ovarian fibromas are typically bilateral and multinodular, associated with calcifications, and present in childhood. In contrast, sporadic ovarian fibromas, which are benign neoplasms accounting for approximately half of all sex-cord stromal tumors, can present at any age (mean, 48 years), and typically present as a unilateral ovarian mass. Benign entities that enter the differential diagnosis include thecoma, sclerosing stromal tumor, leiomyoma, and mitotically active cellular fibroma. Mitotically active cellular fibroma is a newly defined histologic subtype of ovarian fibroma characterized by hypercellularity and increased mitotic rate of 4 or more per 10 high power fields. A malignant diagnosis should not be rendered on the basis of mitotic count alone. Malignant tumors in the differential diagnosis with ovarian fibroma include adult granulosa cell tumor, endometrial stromal sarcoma, and leiomyosarcoma.