Minor trauma to the head or neck is occasionally followed by severe chronic headaches. We have evaluated 35 adults (27 women, 8 men) with no prior history of headaches, who developed recurrent episodic attacks typical of common or classic migraine following minor head or neck injuries ("post-traumatic migraine"-PTM). The median age of these patients was 38 years (range 17 to 63 years), which is older than the usual age at onset of idiopathic migraine. The trauma was relatively minor: 14 patients experienced head trauma with brief loss of consciousness, 14 patients sustained head trauma without loss of consciousness, and 7 patients had a "whiplash" neck injury with no documented head trauma. Headaches began immediately or within the first few days after the injury. PTM typically recurred several times per week and was often incapacitating. The patients had been unsuccessfully treated by other physicians, and there was a median delay of 4 months (range 1 to 30 months) before the diagnosis of PTM was suspected. The response to prophylactic anti-migraine medication (propranolol or amitriptyline used alone or in combination) was gratifying, with 21 of 30 adequately treated patients (70%) reporting dramatic reduction in the frequency and severity of their headaches. Improvement was noted in 18 of the 23 patients (78%) who were still involved in litigation at the time of treatment. The neurologic literature has placed excessive emphasis on compensation neurosis and psychological factors in the etiology of chronic headaches after minor trauma. Physicians must be aware of PTM, as it is both common and treatable.