✓ The authors report a case of cystic choroid plexus papilloma that originated in the posterior fossa. No connection with the ventricular system was found intraoperatively. Magnetic resonance (MR) and computerized tomography imaging did not furnish a diagnosis, but findings of pathological examinations were consistent with those of choroid plexus papilloma. The authors describe the different appearances of the tumor on MR images and discuss the differential diagnosis with other tumors of the posterior fossa.