Choroid plexus carcinomas are extremely rare in adults. They can behave aggressively and their optimal management is uncertain. A 35-year-old woman was admitted with an episode of loss of consciousness. Magnetic resonance imaging showed a homogeneously enhancing mass in the trigone of the right lateral ventricle. Detailed examinations found no evidence of an extraneural primary focus. She underwent total removal of the tumor. Pathological diagnosis was confirmed as a choroid plexus carcinoma. She is doing well eight months after surgery.