The age-adjusted lung cancer incidence rates among Japanese, Chinese and Hawaiian women in Hawaii do not correlate to their respective cigarette smoking exposures. We conducted a case-control study to determine the lung cancer risk associated with smoking among these three ethnic groups of women by reviewing the medical records of 176 Japanese, 67 Chinese and 132 Hawaiian lung cancer patients diagnosed from 1968 to 1978. Smoking histories, as well as socioeconomic indexes, for these cases were compared to those of 2,404 sex- and race-matched controls from the general population. Controlling for age and socioeconomic index, we found that lung cancer risk associated with smoking was greatest for Hawaiian (O.R.=10.5), less for Japanese (O.R.=4.9) and least for Chinese women (O.R.=1.8). While smoking was associated with a significant increase in lung cancer risk for all histologies among Japanese and Hawaiian woman, the risk was much greater for epidermoid and small-cell types than for adenocarcinoma. Among Chinese women, epidermoid and small-cell lung cancer were the only histologies showing a significant association with smoking. There was some suggestion that increased lung cancer risk was associated with a higher socioeconomic index after controlling for age and smoking, at least among Japanese born in Japan and Hawaiians with adenocarcinoma. The population risk for lung cancer attributable to smoking was found to be 79% for Hawaiian women, but only 44% for Japanese and merely 11% for Chinese women. Thus, we concluded that the majority of lung cancer occurring in Japanese and particularly Chinese women in Hawaii is due to factors other than cigarette smoking.