Splenocytes harvested from mice that underwent chemical axotomy (by 6-hydroxydopamine) or that had electric lesions in their anterior hypothalami demonstrated a significant decrease in their proliferative ability after concanavalin-A stimulation in vitro. In axotomized mice pre-treated with cyclophosphamide, faster restitution of the proliferative activity was observed on days 6-8 after the drug's administration. Splenocytes isolated from mice treated with 6-hydroxydopamine did not exhibit any suppressive activity, which is characteristic of the restitution period following administration of cyclophosphamide. These results indicate that the autonomic nervous system exert a direct effect on immunoreactivity and on processes which are responsible for restitution after cyclophosphamide-induced immunodisorders.