Korean American adolescents are a population that may be particularly vulnerable to mental health problems because of the potential cultural conflicts they face during an important developmental period. Yet little is known about the prevalence of their mental health problems. The aims of this study were to determine the prevalence of various mental health problems in a sample of Korean American adolescents, and to identify whether gender or age of the youth are associated with the types or severity of their mental health problems. This cross-sectional study included 138 Korean American adolescents from community settings in California. A demographic questionnaire and the Youth Self Report (YSR) were completed by adolescents. Descriptive analyses and t-tests were used to examine the aims. Percent of the sample falling into "normal", "borderline", and "clinical" ranges for different mental health problems was also determined based on normative scores provided in the YSR manual. Results indicate that 18% of the Korean American adolescents experienced clinically significant mental health problems. Most problems were of the internalizing type such as anxiety and depression where almost 23% of the youth reached the cutoff for clinical significance. The youth also experienced high levels of social problems, thought problems, and attention problems. However, scores for somatic complaints, rulebreaking behavior, and aggressive behavior as well as the composite score for externalizing problems were in the "normal" range. Girls reported higher levels of anxiety/depression and somatic complaints than boys, contributing to their higher internalizing score as well. Boys and older adolescents reported higher levels of rulebreaking behavior. A substantial percent of Korean American adolescents in this sample reported symptoms of anxiety and depression, especially girls. Findings suggest the need to screen for these problems in pediatric care and for development of prevention and referral programs in Korean American communities.