Substance use among sheltered adolescents is very serious in South Korea--a nation in the process of rapid industrialization and urbanization. However, few studies have investigated substance use among the adolescents which is a growing concern of the changing society of this nation. This study examined the prevalence of substance use and explored risk factors that predict substance abuse by sheltered adolescents. Through a questionnaire survey of sheltered adolescents, data on substance use and the risk factors were collected. The sample of the adolescents included 44 (33.3%) males and 88 (67.2%) females; their mean age was 15.8 years (SD = 1.62). The results of a logistic regression analysis showed that alcohol expectancy, physical abuse, and peer pressure were all statistically significantly associated with substance abuse. Findings on the critical issues are expected to lead to the development of urgently needed prevention programs for the high-risk adolescents in South Korea. (Contains 3 tables.)