Despite increasing research on the relationships between acculturation and health, it is unclear whether (1) ethnic group variation occurs in acculturation-health relationships, (2) acculturation components vary differently in relationship to health, (3) biculturalism has beneficial effects on health and (4) multidimensional health relationships occur with acculturation. This study examined the Korean American ethnic group, considering how acculturation was related with five dimensions of health: smoking, physical activity, fat intake, body weight, and reported health. Pretested questionnaires were mailed to a national sample with Korean American surnames, and 55% of the deliverable sample responded, producing 356 usable questionnaires. Acculturation was measured using a two-culture matrix model and Gordon's theoretical work, and showed three distinct groups (acculturated, bicultural and traditional) and four components (American structural, American cultural, Korean structural and Korean cultural). Bicultural men were least likely to smoke, while acculturated and bicultural women were more likely to smoke than traditional women. Korean structural and cultural components were related to men's smoking. Higher acculturation was related to light physical activity, but not to vigorous physical activity. Fat intake did not differ by acculturation status. Higher acculturation was associated with higher body weight and better self-reported health only in men. Higher American cultural component scores were associated with better self-reported health in men. Among Korean Americans, acculturation components varied in their relationships with health, beneficial effects of being bicultural on health were not found, and acculturation-health relationships were multidimensional. Overall, ethnic group variation in health occurred, with Korean Americans similar to some ethnic groups but different than others. Future health research and practice can benefit by acknowledging the complexity of acculturation and its multidimensional effects on health.