During the period from July 1977 to June 1980, 75 patients underwent the surgical excision of solitary brain metastases, and 61 of these patients received whole brain radiation. Three patients developed chronic radiation necrosis. In the 3 patients with necrosis, computed tomography suggested recurrent tumor; the histological diagnosis of necrosis only was obtained at operation in 2 of these patients and by autopsy in the third. Radiation damage resulted in the death of 1 patient, a chronic vegetative state in another, and severe neurological deficit in the third. An additional 4 patients had neurological complications probably related to radiation therapy. As the survival of such patients is prolonged by aggressive treatment, the incidence of radiation-induced complications is likely to increase. The optimal dose of radiation necessary to destroy microscopic foci of tumor after the surgical resection of a single brain metastasis is unknown. Because of the significant incidence of damage after radiation as currently delivered, studies using graded, lower doses are indicated.