Objective: This study was designed to investigate whether the stroke occurrence is influenced by the seasonal and diurnal changes and also to know if the seasonal factor affects the functional outcome of stroke patients.

Method: We analyzed the epidemiologic, etiologic, and clinical data collected from the chart reviews in 824 stroke patients who were admitted to the Asan Medical Center from April 1995 to May 1997.

Results: The highest incidence of the stroke was noted in the group of 60 years of age with the ratio of male to female, 1.27 : 1. The occurrence rate of ischemic stroke (60.4%) was higher than that of hemorrhagic stroke (34.9%) or other type stroke (4.7%).

The highest occurrence of stroke was noted during the months of January and November. The seasonal preference was winter and autumn followed by summer and spring. The onset of stroke was relatively high between 6:00 am and 6:00 pm with regard to the diurnal variance. The functional improvement was not significantly affected by the seasonal change.

Conclusion: The stroke occurred more in winter and autumn than in other seasons. And the functional recuperation was not influenced by the seasonal variation. A further multicenter prospective study using stroke registry would bring more precise and valuable informations.