Pathological findings relating to lung cancers removed surgically from women at the Kowloon Hospital (KH), Hong Kong, and the Cancer Institute Hospital (CIH), Japan (77 and 54 cases respectively), were examined in order to clarify possible differences between Hong Kong Chinese and Tokyo Japanese women. Adenocarcinoma was the most frequent subtype encountered in both hospitals, but the rate was higher in CIH (90.9% in CIH and 68.8% in KH); that of large-cell carcinoma was second in KH where the rate was higher (14.3% in KH and OYo, in CIH). A remarkable difference was observed in the location of adenocarcinomas; the percentages of central and peripheral types were 60.4% and 24.5% respectively in KH, but 4% and 96% respectively in CIH. The proportion of the central type (45.5%) was higher than that of the peripheral type (27.3%) in large-cell carcinomas of KH. The number of adenocarcinomas having a bronchiolo-alveolar pattern (which is observed more frequently in peripheral-type adenocarcinomas) was higher in CIH (50%) than in KH (17%). Tall columnar cells were observed more often in KH (43. I Yo in KH and 20.8% in CIH), and hobnail and cuboidal cells more often in CIH (31.4 and 80.4% respectively in KH, and 54.2 and 95.8% respectively in CIH). The difference may be explained by the frequent presence of tall columnar cells in the glands of central carcinomas, and hobnail and cuboidal cells in peripheral adenocarcinomas. The frequent occurrence of the central type of adenocarcinoma and large-cell carcinoma appears characteristic of the lung carcinomas removed from women in Hong Kong. This suggests the existence of exogenous causative agents for lung cancer in Hong Kong females.