An experimental "healthy lifestyle programme" was initiated in Year 7 (first year of high school) in selected high schools in 1980 and was conducted over a three-year period. The programme had two main objectives: to influence attitudes and increase knowledge about health matters, in order to improve lifestyle; and to strengthen the general case for the more organized instruction of schoolchildren in this field. As part of the programme, children were given lessons on nutrition, physical activity and fitness, and on alcohol, tobacco and drugs. The programme was reasonably implemented in three of the four schools which took part in the experiment. Significant improvements, over three years, in attitudes and knowledge about health and nutrition and a reduction in cigarette smoking, were noted among children in schools where the programme had been implemented reasonably. The reasons for the partial success of the programme are discussed.