The problem of tobacco, alcohol and drugs was investigated in various boarding schools in Switzerland. The number of smokers among 297 pupils in the Canton of Obwalden rose from 53% in the 12-14 year old children to 58% (15-17 years) and to 60% (18-20). In the St. Galler Oberland, 39% of the 12-13 year old children smoked and 48% of those aged 14-15 years; 75% of the younger and 64% of the older pupils preferred a glass of milk to a glass of alcohol. In the Canton of Neuchatel, 53% of 174 pupils aged from 15-17 were smokers; 10% had already tried drugs once. In the Canton of Graubunden, 33% of the 13-15 year old pupils and 34% of those aged 17-19 from a total of 166 smoked regularly or occasionally; none of the younger, but 8% of the older pupils had already tried drugs once. Of 412 Swiss pupils in boarding schools, 35% were smokers at the age of about 15-16, 52% at 17-18 and 68% at 19-20 years of age.