Nine patients with autonomic dysfunction syndrome (ADS) characterised by sympathetic discharge and extensor posturing are presented. Morphine was given to three patients and in all cases consistently stopped the episodes. Dantrolene was given to one patient and reduced the severity of the extensor posturing without affecting the other components of the ADS. Bromocriptine was given to three patients and appeared to have both short- and long-term effects. Acutely, the drug partially corrected the hyperthermia and diaphoresis associated with these episodes. Two patients were given bromocriptine long-term. In one patient, the ADS was completely controlled and in the other, the frequency of the episodes decreased. The autonomic dysfunction syndrome appears to be related to both severe closed head injury and acute hydrocephalus. The clinical similarity of the two diverse etiologic groups and the absence of precipitating increased ICP in the former suggests the common theme is a release of the brain stem from higher control. The responses to morphine and bromocriptine suggest that the opiate and dopaminergic pathways play roles in the entity.