Introduction: Brenner tumors (BTs) make up about 1-2% of all ovarian neoplasms. About 95% of BTs are benign. Borderline and malignant BT make up the remaining 5%. The median age at presentation is about 50 years. Most patients are asymptomatic and these slow-growing tumors are often discovered incidentally in ovaries removed for other causes. Some patients present with signs of hyperestrinism such as post-menopausal bleeding if the tumor has functioning stroma. Gross: BTs are generally unilateral (< 10% are bilateral), variably-sized, solid, firm tumors. They rarely exceed 10 cm in size. They are sharply demarcated with a nodular yellow-white cut surface (as seen here). There may be small cystic spaces filled with viscous yellow-brown secretions. About 25% of cases are associated with other tumor types, most commonly mucinous variety. Image courtesy of : Ed Uthman, MD, Houston, Texas.