A culture procedure for dorsal root ganglion (DRG) cells is presented using a completely defined culture medium without antibiotics, in combination with mechanical dissociation procedures. This culture procedure allows all dorsal root ganglion cell types to be cocultured for periods of at least 106 days. Some of the dorsal root ganglion neurons, which could be identified by their neurofilaments and the presence of fluoride resistant acid phosphatase, regained their original T-cell appearance within two weeks. After one month in culture ganglion-like reaggregates appeared. Schwann cells, satellite cells and fibroblasts were identified using morphological criteria. All neurons tested maintained excitability during, at least, the first 35 days in culture, since in all cases action potentials could be evoked by current pulses. The method has proved to be useful in the study of morphological, cytochemical and electrophysiological aspects of dorsal root ganglion cell differentiation in vitro.