Eight hundred hybridoma lines were generated from mice immunized with the fixed gray matter of cat spinal cord. Of these lines, 47 were positive when screened immunohistochemically against sections of the cat spinal cord. Twenty-nine lines secreted antibodies that bound to neuronal antigens. Of these, 16 bound to axons only, 8 bound to axons and cell bodies, and 5 bound to cell bodies only. Eighteen lines secreted antibodies that bound to glial cells. Five lines that secreted antibodies that intensely stained spinal cord sections were cloned and screened against other parts of the central nervous system. Each of these five antibodies bound to specific subsets of neurons. For example, in the spinal cord, one antibody (Cat-301) recognized a surface determinant on the dendrites and cell bodies of neurons that, in morphology and location, resemble long-distance projection neurons. A second antibody (Cat-201) recognized an antigen in axons and in the cytoplasm of neuronal cell bodies that may be a subset of those recognized by Cat-301. A third antibody (Cat-101) recognized only axons. The subcellular localization of the antigen recognized by each antibody is the same in all areas of the central nervous system we have examined. The fact that each of the antibodies described here has a restricted distribution in the central nervous system shows that there is a high degree of molecular diversity among vertebrate neurons and that hybridoma technology can be used to explore this diversity. This class of reagents should be a useful addition to the many established techniques for studying the organization of the vertebrate central nervous system.