Due to the recent reported increase in incidence rates of adenocarcinoma and the weaker relationship of this histological type to smoking, a study was undertaken to investigate changes over time in smoking and lung cancer histology. Medical records of 428 Jewish male lung cancer patients from 1957 to 1985 were studied for smoking history and histological diagnosis. No time trend was found in the smoking-histology relationship, although in this study adenocarcinoma was found to be strongly related to smoking in all periods. Thus, the increase in adenocarcinoma reported in Israel is not the reflection of less smoking or a change in the smoking-adenocarcinoma relationship. It is postulated that changes in the type of cigarettes smoked might be responsible for the change in the incidence of histological types.