The unexpected finding of hyperamylasemia in a patient with isolated head injury prompted a study of amylase levels in patients with various degrees of cranial trauma. None of seven patients with isolated maxillofacial trauma had hyperamylasemia. This group was studied to discount injury to salivary glands as a source of elevated amylase levels. Only one of ten patients with simple cranial injury without computerized tomographic (CT) scan evidence of intracranial bleeding had hyperamylasemia. Six of ten patients with CT scans positive for intracranial bleeding had hyperamylasemia. Isoamylase analysis showed that the source of the hyperamylasemia was varied. These results suggest a central neural control of serum amylase levels. The reliability of the serum amylase level as an indication of pancreatic trauma in a patient with concomitant head injury is questioned.