The purpose of this study was to determine the value of primary cell culture in combination with histololgical techniques as a method for the diagnosis of central neurocytoma ; it involved three patients who underwent resection at our hospital and three seen during consultation. Sterile fresh tumor tissues were mechanically and enzymatically dissociated into individual cells and seeded onto poly-L-lysine precoated Aclar coverslips. The cells attached to the surface of the coverslips within 12 to 24 hours, and a delicate cytoplasmic process developed within two to three days of preparation. Immunocytochemical stains for synaptophysin and MAP2 were strongly positive in the cultured tumor cells, and electron microscopic examination also supported their neuronal origin. Cell culture can thus be used as a rapid, reliable and reproducible method for the diagnosis of central neurocytoma, and may be valuable for the diagnosis of small round cell tumors localized in the intra- or periventricular region of the brain.