Between 1992 and 1994, an interventional program was held in the secondary schools ("Hauptschulen") in Düsseldorf contra cigarette smoking. The program was conducted in the following way. Half of the schools (intervention schools) were involved in this program which consisted of 15 sessions. The other schools served as control groups. During the first year of this program school-teachers and a physician taught students about the function and the abilities of the healthy heart and lung. The students developed adversions to smoking. In addition, the students learned by role-plays how to say no to a cigarette without embarrassment. These role-plays were videotaped. During the second year of this program the role-plays were repeated and teaching about the heart and the lungs was augmented. Also, every student got the opportunity to meet and talk with a famous athlete. Furthermore, smoking-cessation programs were hold in four intervention schools. The program started in the sixth grade with a questionnaire administered to 878 schoolchildren. During this time the average age of the children was 13 years. Because of a large fluctuation, the questioning could be repeated with only 630 of these children (71.8%) after 2 years. At the end of the study the number of smokers had increased two times greater in the control schools than in the intervention schools (boys: 20.5% points vs 9.4% points; girls: 44.3% points vs 21.0% points). Obviously, the continuation of the program during the second year was important in making the program successful. Among the participants of the intervention program there was a trend to stop smoking. But the program was not able to prevent non-smokers from starting the habit. On the other hand, of the children who started smoking during the program, more girls in the intervention schools quit smoking than in the control schools. At the end of the program more girls than boys (mean age 15 years) smoked. Almost one-fourth of the boys, and from the control schools one-third of the girls were already daily smokers. The smokers obtained cigarettes from kiosks, from friends, vending machines, vendors or shops, but seldom from their homes.