The present study describes ganglia and isolated neurones in the ovary of the Wistar rat, employing histological and histochemical techniques. Four kinds of ganglia in the postpubertal and young adult rat were identified: the mesovarial, hilar, medullary and cortical ganglia. Isolated neurones were also found, being dispersed along blood vessels in the ovary medulla and near the follicles. The soma diameters of these neuronal cells ranged from 25 to 50 microns. In the prepubertal rat, only the mesovarial and hilar ganglia were observed. They contained small neurones with soma diameters ranging from 10 to 15 microns. NADPH-diaphorase activity was detected in some isolated neurones and in the cortical and hilar ganglia in all rats examined.