Review of the histology of 219 lung cancers initially diagnosed at Lutheran General Hospital, Park Ridge, Illinois, in 1963-1967 and 1974-1976, confirms the increasing incidence of adenocarcinoma. This is due to an increase of adenocarcinoma in men. In women, the incidence of adenocarcinoma was higher than squamous carcinoma in the earliest period (44% adeno, 18% squamous). The percentage of women with lung cancer has also significantly increased from 19% to 31%, which increases the overall incidence of adenocarcinoma of the lung. As the number of women with lung carcinoma has increased, there has been no change in the percentage of adenocarcinoma in women.