While secondary erythrocytosis is often associated with tumors arising from the kidney, other tumors have been described to originate in the liver, uterus, ovary, adrenal gland, and central nervous system, among which cerebellar hemangioblastomas are involved in most instances. Two cases of meningioma associated with erythrocytosis have already been reported. We observed a 59-year-old female patient who had developed a frontal meningioma associated with erythrocytosis. Before surgery, she had a significantly elevated total red blood cell volume with a normal plasma volume. Serum erythropoietin (Epo) dosage assessed by radioimmunoassay was within the normal range. The tumor was removed and the pathologic study found a meningotheliomatous meningioma. Total RNA from the tumor was hybridized to a monkey cDNA Epo probe. A strong 1.6-kb messenger RNA (mRNA) signal was observed, which is the expected size of human Epo mRNA. In situ hybridization with the 35S-labeled Epo probe was performed on frozen tumor tissue sections. A significant hybridization was observed in all the tumor cells, whereas the stroma was negative. Therefore, in this meningioma associated with erythrocytosis, Epo was produced by the tumor cells themselves.