A retrospective analysis of the cases of 173 patients operated on for aneurysms and admitted to a neurosurgical service early after subarachnoid hemorrhage was conducted with respect to white blood cell (WBC) count and highest daily temperature. Daily trends for the development of clinically significant vasospasm (VSP) as well as mortality during the hospitalization were analyzed. An admission WBC count greater than 15 x 10(9)/l was associated with 55% mortality as opposed to 25% mortality for those with a lower WBC count. The mortality of those with a temperature greater than 37.5 degrees C on Day 0 was 60%, compared with 35% for those with a lower temperature. A WBC count greater than 15 x 10(9)/l on Day 0 was associated with a VSP rate of 40%; a lower WBC count was associated with a VSP rate of 30% Day 0 temperatures greater than 37.5 degrees C were associated with a VSP rate of 40%, while patients with lower temperature had a VSP rate of 30%. By Day 6, the patients with temperatures greater than 37.5 degrees C had a VSP rate of 60%, double that of the VSP rate of those with temperatures less than 37.5 degrees C. WBC count was apparently more closely linked to the chance of dying than the chance of developing VSP. The development of fever after a few days is related to both increased mortality and increased chance of developing VSP.