A case of akinetic mutism was reported with reference to a marked improvement by levodopa, bromocriptine and trihexyphenidyl. A 39-year-old male, first seen on February 2, 1981, had an occipitalgia, accompanied by nausea and vomiting. For several months before this consultation, the patient had suffered from asthenopia. Brain CT scan and cerebral angiogram demonstrated internal hydrocephalus due to aqueduct stenosis of unknown etiology. After a ventriculoperitoneal shunt operation on February 20, 1981, he completely recovered. Two years and a half after the shunt insertion he had no difficulty in his daily life. He reentered the hospital on December 21, 1983, because of personality change, mental deterioration and bradykinesia. Brain CT scan showed recurrent hydrocephalus resulting from shunt blockage. Following the shunt revision, hydrocephalus was resolved. Nevertheless, the patient did not return to his previous state. And he became bed-ridden, incontinent of urine, and unable to take fluids or foods, following which he went into a state of akinetic mutism. Other neurological findings were as follows: upward gaze palsy, impaired convergence, convergence nystagmus, plastic rigidity of neck and all four limbs, and diffuse hyperreflexia with right Babinski's sign. Abnormal involuntary movement was not seen. On March 27, 1984, levodopa therapy was instituted and on April 2, trihexyphenidyl was combined with levodopa. Shortly after administration of levodopa and trihexyphenidyl, akinetic mutism began to improve, but upward gaze palsy was not affected. He began to speak and could walk unassisted by the end of July.(ABSTRACT TRUNCATED AT 250 WORDS)