Mortality trends and ecological data strongly suggest that the lung cancer risk associated with smoking is greater among Hawaiians than among the other ethnic groups in Hawaii. The authors combined data from two consecutive population-based case-control studies to formally test this hypothesis among 740 cases and 1616 controls. A multiple logistic regression analysis adjusting for pack-years of smoking, occupation, education, and age revealed that Hawaiian, Filipino, and Caucasian male smokers were at 121%, 53%, and 46% greater risk for lung cancer than Japanese male smokers. These risk differences were statistically significant, were consistent across sexes and histological types, and were not explained by the type of cigarettes, the level of inhalation, or by cholesterol or beta-carotene intake. Additionally, an increased lung cancer risk unrelated to smoking was observed among Chinese women. The possibility that other dietary antioxidants and/or genetic risk factors are responsible for these ethnic differences needs to be investigated.