Epidermal growth factor receptor (EGF-R) were assayed by 125I-EGF binding in 28 surgical samples of human meningiomas. High affinity EGF-R were found in 26/28 tumors (92 p. 100) at concentrations ranging from 20 to 410 femtomoles per mg of membrane protein (fmol/mg prot. mb.). In 18/26 cases (64 p. 100), the EGF-R concentration was between 95 and 230 fmol/mg prot. mb. No relationship was found between the EGF-R level and the site or histopathology of the tumor. The only noticeable observations were the low levels of EGF-R in the 3 anaplasic meningiomas as compared to the whole population and the undetectable level of EGF-R in the angiomatous tumors. In addition, no correlation was found between EGF-R levels and the hormonal status of the patients, nor between EGF-R levels and the intratumoral concentration of progesterone receptors assayed simultaneously. The biological relevance of EGF-R in meningioma is discussed in this context.