The expression of epidermal growth factor receptor (EGF-R) was examined in 27 primary human brain tumors (7 glioblastomas, 10 astrocytomas, 5 oligodendrogliomas, 1 schwannoma, 1 ganglioneuroma, 1 medulloblastoma, 1 ependymoma, 1 histiocytic lymphoma), in 6 brain metastases from lung carcinomas and in 20 meningiomas. Peritumoral tissues histologically normal excised surgically along with a large tumor were used as control. All plasma membranes from brain tissues tested showed specific EGF binding. The EGF receptor is expressed at low levels in the control human brain and at very high levels in 60% of the total intracranial tumors studied. When the various histological types of tumors were analyzed, the higher percentage of positive tumors was found with the meningiomas (85%) and the glioblastomas (71%), while the lower percentage of positivity was found with the oligodendrogliomas (40%) and the astrocytomas (30%). A good correlation between binding and total amount of EGF-R protein detected by Western Blot was also observed