The current study describes the presence of neuroendocrine antigens of peripheral and central neural tumors using eight monoclonal antibodies raised to small cell lung carcinoma (SCLC), which recognize "neural/neuroendocrine" or "neural" antigens, as defined by their reaction pattern in normal tissues and tumors. At least five of them recognize different epitopes of the neural cell adhesion molecule (N-CAM). It was found that all of 12 neuroblastomas, 2 ganglioneuroblastomas and 4 ganglioneuromas as well as 23 central primitive neuroectodermal tumors, 13 astrocytomas and 4 ependymomas share "neural/neuroendocrine" antigens (as defined by the anti-N-CAM antibodies Moc-1, -21, -32, -52 and -191) with SCLC. The "neural/neuroendocrine" antigen defined by Moc-171 was also found in all peripheral tumors, but only in further differentiated central tumors. Non-N-CAM related "neural" antigens (as defined by Moc-51 and -172) were found only in better-differentiated peripheral and central tumors, but they could be demonstrated in all three medulloblastoma cell lines studied. In addition, the antigen defined by Moc-51 was demonstrated in an immunoblot of a neuroblastoma cell line. Antibodies recognizing "epithelial" antigens of SCLC and other epithelia and their tumors (Moc-31 and -181) were non-reactive. It was concluded that these findings give further support for a relation between neural and neuroendocrine tumors and that some of the antibodies may be useful for the detection of differentiation in neural tumors. Antibodies with an "epithelial" recognition pattern may serve to distinguish neural from neuroendocrine tumors.