Objective : This study was aimed to investigated the correlation between the stroke incidence by day of the week and risk factors in acute stroke patients. Methods : From October in 2005 to October in 2007, 673 acute stroke patients wereincluded. Patients were hospitalized within 14 days after the onset of stroke in DongGuk University International Hospital, Kyungwon University In-cheon Oriental Medical Hospital or the Department of Cardiovascular and Neurologic Diseases (Stroke Center), Kyung Hee University Oriental hospital. We investigated general characteristics, stroke types, age group, educational backgrounds, medical history, lifestyle (the impact of stress, exercise, smoking and drinking) and Sasang constitution according to the stroke incidence by day of the week. Results : After examining each participants with day of the week, the order of days by incidence was Monday, Wednesday, Sunday, Saturday, Tuesday, Thursday and Friday respectively. Monday and Tuesday showed the highest ratio. As the aspect of demographic data of subjects, the group under 55 years and from 55 years to 70 years showed the highest ratio on Monday. In the group between 25 years to 55 years, the ratio, by the classification of actual productive age, was statistically higheron Monday. In addition, the ratio showed statistically higherby educational background, from elementary school to high school and over high school. In regard tothe medical aspect, incidence of cerebral hemorrhage showed higher ratio on Sunday, and incidence of brain infarction was higheron Monday. However, there was no difference of the past history between the two groups. With regard tothe aspect of lifestyle of subjects, the group with huge stress before the incidence of stroke showed a higher ratio of stroke incidence on Monday. Participants who didn't exercise regularly and participants who didn't smoke or drink showed higher ratio of stroke incidence on Monday. However, this was not important statistically. In regard to the aspect of Sasang constitution, Soeumin showed the highest ratio of stroke incidence on Wednesday, Taeuminon Monday, and Soyangin on Saturday and Monday. Conclusion : According to these results, several cardiovascular risk factors affect stroke incidences on Monday. Further studies will be needed to help understand the correlation between stroke incidence by day of the week and risk factors in acute stroke patients.