Antisera were prepared against a clonal line (PC12) of rat pheochromocytoma cells that were grown in either the presence or the absence of nerve growth factor (NGF). PC12 cells respond to NGF by growing neurites and express many differentiated properties of adrenal chromaffin cells and sympathetic neurons. The antisera, after absorption with rat liver, kidney, spleen, and thymus, reacted in the micro-complement fixation and indirect immunofluorescence assays with PC12 cells (both NGF-treated and untreated), brain, adrenal medulla, and superior cervical ganglia, but not with a variety of other tissues. Cross-absorption of the antisera with brain and adrenal medulla indicated the presence of components that were specific to brain, adrenal medulla, and PC12 cells. Brain-specific and adrenal-medulla-specific antigens were also detected in other species, such as rabbit, cat, and mouse. No differences could be detected in the specificity of antisera raised against either NGF-treated or untreated PC12 cells. Indirect immunofluorescence on live cells also detected cell surface antigens on both cell bodies and processes. These results suggest that such antisera may be used to detect, localize, and identify specific neural and adrenal medullary antigens.