OBJECTIVES: To date, studies have not comprehensively demonstrated the relationship between stroke incidence and socioeconomic status. This study investigated stroke incidence by household income level in conjunction with age, sex, and stroke subtype in Korea. METHODS: Contributions by the head of household were used as the basis for income levels. Household income levels for 21 766 036 people were classified into 6 groups. The stroke incidences were calculated by household income level, both overall within income categories and further by age group, sex, and stroke subtype. To present the inequalities among the six ranked groups in a single value, the slope index of inequality and relative index of inequality were calculated. RESULTS: In 2005, 57 690 people were first-time stroke patients. The incidences of total stroke for males and females increased as the income level decreased. The incidences of stroke increased as the income level decreased in those 74 years old and under, whereas there was no difference by income levels in those 75 and over. Intracerebral hemorrhage for the males represented the highest inequality among stroke subtypes. Incidences of subarachnoid hemorrhage did not differ by income levels. CONCLUSIONS: The incidence of stroke increases as the income level decreases, but it differs according to sex, age, and stroke subtype. The difference in the relative incidence is large for male intracerebral hemorrhage, whereas the difference in the absolute incidence is large for male ischemic stroke.