Little is known of the molecular genetic mechanisms contributing to meningioma tumor progression. We evaluated a total of 26 clinical cases of meningioma: twenty three patients with meningioma treated at our institution between 1978 and 1990 and three asymptomatic cases found initially at autopsy. In addition, histologically normal meninges obtained at post-mortem examination from 5 cases were evaluated. There were 13 men and 10 women in the patient group with a median age of 48.7 years, treated by surgery and/or irradiation. Median follow-up was 46 months (range 16-152 months). Archival cases and age-matched normal meningeal tissue obtained at autopsy during the same time period were obtained for study. Patients with TGF alpha scores greater than 3.0 were more likely to fail treatment and had lower overall survival times than those with immunostaining scores of 1 or 2. Three autopsy cases where meningioma had been silent clinically had overall staining scores of 0.75, while 10 samples of normal meninges harvested from 5 cases at autopsy had staining scores of 0. Two patients each underwent 3 surgeries for recurrent tumor, serial specimens showed increased TGF alpha expression over time, though all material from these procedures was consistent with the diagnosis of histologically benign meningioma.