The MR imaging appearance of neuroepithelial cysts in the lateral ventricle is reported. Two cases of proven and two of presumed intraventricular neuroepithelial cysts are presented. In one case, MR observations documented spontaneous regression of a large intraventricular cyst. Theories regarding the origin of neuroepithelial cysts are briefly reviewed. Standard T1- and T2-weighted spin-echo pulse sequences were used to study cysts in the lateral ventricles in axial, coronal, and sagittal planes. The cyst wall can be demonstrated reliably with MR images, eliminating the need for CT and/or contrast ventriculography. MR may also be useful in monitoring cyst size on serial examinations.