A method has been developed for the long-term culture of dissociated adult mouse dorsal root ganglia (DRG). Of critical importance to the success of this technique was a three-hour incubation in collagenase which softened the DRG and permitted gentle dissociation. The morphological and electrophysiological features of the dissociated adult DRG were similar to those observed in previous studies of immature (i.e., embryonic and newborn) DRG in culture and also to those of adult DRG in situ. With regard to electrophysiological work, the adult DRG neurons are superior to embryonic and newborn neurons because of their larger size and greatly increased survival in culture (no degeneration for first six days, and thereafter a relatively slow decrease). The adult neurons regenerated nerve fibers to an extent comparable to that of immature neurons. Therefore, the adult DRG cultures might be useful to study factors influencing regeneration in the adult mammalian nervous system. The adult cultures might also be useful to investigated factors influencing the aging process.