Two cases with epidermoid and one case with dermoid in the 4th ventricle were treated in our clinic during the last one year. The clinical findings in these three cases were described, and dermoid and epidermoid tumors in the 4th ventricle were discussed dealing with the incidence and the characteristic features of the findings in CT scanning. The correct diagnosis of both epidermoid and dermoid in the 4th ventricle was done by CT-scanning which showed an irregular low density area of EMI No. -4 approximately 12 in the posterior fossa without any contrast media enhancement. The low density lesion could be differentiated by both angiogram and ventriculogram from arachnoid cyst, ependymoma, cystic astrocytoma and cystic hemangioblastoma in the 4th ventricle. Total removal of the tumor was performed on 2 cases, and a part of the tumor capsule attached to the medulla oblongata was left in the other case. All patients returned to their own job after operation.