Patients in the early stage of severe head injuries occasionally present with a clinical picture analogous to that in vascular or neoplastic pontine lesions and they can be identified by careful clinical examination and by repeated electroencephalography (E.E.G.). The commonest features in these cases were preservation of consciousness, constriction of the pupils, disturbances of reflex ocular motility, severe pyramidal deficits, decerebrate rigidity, myoclonic manifestations, irregular breathing, and cranial nerve palsies. An E.E.G. tracing similar to the normal pattern was a common finding. These observations suggest that pontine syndromes may be directly produceg a non-reacting, but conscious, patient for one who is deeply comatose.