Neuron-specific enolase (NSE) is an enzyme involved in glycolysis and has a gamma-subunit. It is localized in neurons and axonal processes, and escapes into the blood and cerebrospinal fluid at the time of neural injury. In this study, the serum NSE levels in cases of subarachnoid hemorrhage (SAH) and intracerebral hemorrhage (HIH) were measured. The subjects were 20 patients with subarachnoid hemorrhage (mean age; 53.4 +/- 14.5, 12 men and 8 women) and 20 with hypertensive intracerebral hemorrhage (mean age; 57.9 +/- 13.6, 11 men and 9 women). Although the serum NSE levels of all of these patients were measured on admission, measurement in patients with SAH were serially measured for an additional three weeks. There was no correlation between the serum NSE levels on admission in patients with SAH and consciousness level or clinical grade on admission, or prognosis. However, in Fisher's CT group 3 or 4, patients showed significantly higher levels of NSE than patients in group 2. Seven patients in whom vasospasm was observed by cerebral angiography during the course of treatment demonstrated elevated serum NSE levels from the 5th to the 15th days. In cases of HIH, there was also no correlation between the serum NSE levels from admission and consciousness level on admission or prognosis. However, the relationship between the size of the hematoma and serum NSE level on admission was significantly higher in patients in whom the maximum diameter was 5cm or more in comparison to those in whom the maximum diameter was less than 5cm.(ABSTRACT TRUNCATED AT 250 WORDS)