In order to determine smoking cessation rates among those who visit medical facilities in Japan, a large-scalefollow-up study was conducted. Subjects were self-reported smokers who visited a cancer hospital, a general hospital,or one of four health checkup facilities in 1997-98. Their smoking habits were followed by two postal surveys. Thefirst was two months after the visit to hospital or attendance at a health checkup screening, and the second was afterone year. In total, 3,552 smokers participated in the present study; 1,131 first visit outpatients at a cancer hospital,214 first visit outpatients at a general hospital, and 2,207 examinees at four health checkup facilities. The responserate for the first follow-up varied from 57.3% to 80.2% of the eligible participants in the six facilities, and that forthe second from 50.0 to 67.1%. When non-respondents were classified as non-quitters, the cessation rate two monthsafter their participation was 11.7% (95% confidence interval, 7.4-16.0%) for the general hospital and 2.7% (2.1-3.5%) for the four health checkup facilities, and those after one year were 9.8% (6.2-14.6%) and 6.0% (5.1-7.1%),respectively. In the cancer hospital, the rate for self-reported cancer patients was 74.6% (68.5-80.0%) after twomonths and 51.3% (44.7-57.9%) one year later. The smoking cessation rate was thus smaller in the health checkupexaminees than in the patients. Outpatients seemed to be more amenable to smoking cessation, and therefore mayconstitute a more appropriate target for cessation programs.