Smoking is a major health risk in young adults. We undertook a study in young Swiss military recruits to determine the impact of intensive training and of help offered on smoking cessation during Basic Military Training (BMT). A questionnaire including questions according to their smoking status, sporting activities and, alcohol use was administered to 999 conscripts at beginning and at the end of the BMT. The results were compared to a control group of BMT schools where no such intervention took place. The study shows that the prevalence of smokers in the intervention group decreased (start BMT 31.9%, end BMT 25.5%; p = 0.021), while the prevalence of smokers increased in the control group (start BMT 26.4%, end BMT 32.6%; p = 0.038). A motivation to serve in the armed forces, as well as the willingness to stop smoking in the next month were the factors associated with a subsequent cessation of smoking during BMT. A smoke stop intervention during BMT is viable and can lead to a decrease in the prevalence of smoking at the end of BMT.