PURPOSE: The aim of this study was to evaluate the clinical characteristics of classic heat stroke in Korea and to identify factors of prognosis for heat stroke by comparing a survival group with a non-survival group. METHODS: We retrospectively analyzed 27 patients with heat stroke who visited the Emergency Department of Kyungpook National University Hospital from March 2001 to February 2005. First, we divided the patients into two groups, the classic heat stroke group and the exertional heat stroke group, and compared them. Second, we compared the survival group with the non-survival group. Age, sex, cause, place where patients were found, underlying diseases, cooling time, performance of endotracheal intubation, initial Glasgow Coma Scale, initial vital sign, and laboratory findings were reviewed. RESULTS: Five of 27 patients in heat stroke died. The classic heat stroke group had 20 patients. They were old and had more patients in the bathroom than the exertional heat stroke group had. The non-survival group showed lower blood pressure, lower initial GCS score, and higher respiratory rate than the survival group. In laboratory findings, the non-survival group also showed lower HCO3-level, lower albumin level, lower glucose level, more prolonged PT, and higher CK-MB level than the survival group. Delay in recognition of heat stroke and cooling were poor prognostic factors in heat stroke. CONCLUSION: The classic heat stroke group had patients who were old and found in the bathroom. Early recognition and treatment of heat stroke is important to reduce mortality. Cooling time, initial GCS score, mean arterial pressure, resipratory rate, HCO3-, PT, CK-MB, and albumin seem to be meaningful when forming a prognosis for heat stroke patients.