An ultrastructural study of the dorsal sympathetic ganglia, chain, and myenteric plexus is described in the streptozotocin diabetic rat after intermittent insulin treatment. The observations described cover the first two weeks following induction of diabetes in which insulin was administered subcutaneously twice daily. Significant regenerative changes were seen with marked axonal sprouting noted at three days. Degenerative changes were seen to be less severe than those in untreated animals. It is concluded that the improvement in the neuropathic changes with insulin treatment supports a transient primary role of the streptozotocin in causing the neuropathy — but that the subsequent improvement seems to be related to the partial control of the diabetes.