Action potentials of single dorsal root ganglion (d. r. g.) cells of cats were elicited by movement of hairs, by pressing on a muscle or tendon through the overlying skin and by slight pressure on the foot pads. Intracellular responses from the d. r. g. cells were different from those from sensory fibers in the ganglion, showing longer rise time, longer duration of the spike, and larger after-hyperpolarization than the latter. In the d. r. g. cells there was neither significant inflexion point on the rising phase of the response nor separation into two components which is often observed in motoneurons. Spontaneous repetitive dis-charge was augmented or depressed by slight pressure on one or another muscle. Post-excitatory depression or post-depression excita-tion was observed following sudden release of stimulation. As the d. r. g. cell deteriorated during the recording, the amplitude of the response decreased gradually but the time course remained relatively unchanged. In the case of motoneurons, the duration of the spike became longer and the inflexion point on the rising phase became more obvious as the amplitude decreased. It was inferred that the potential space between capsular and soma membranes probably keeps the soma in a slightly depolarized condition and makes the threshold of the soma firing lower and also makes it easy to rapidly repolarize the soma and non-myelinated portion within the capsule.