The ministers of education and health have called upon county councils to use their right of ownership to make upper secondary schools smoke-free. The aim of this study was to ascertain changes in the proportion of smoke-free school grounds occurring between 1998 and 2003, to ascertain the number of schools that are planning a ban on smoking on school grounds in the immediate future, to ascertain difficulties of implementation and to compare smoking intensity among students and teachers at schools with different regulatory environments.All headmasters of upper secondary schools in Norway were interviewed over the telephone in 1998 and in 2003.Students were allowed to smoke on school grounds in 71% of the schools in 2003 as against 91% in 1998. Three counties had issued regulations for smoke-free schools during the period. Most schools in these counties had implemented a smoke-free regime; this was the real reason for the national drop. Little change had taken place in schools in the rest of Norway. A majority of the headmasters did not plan to introduce a smoke-free regime on their own. Eight out of ten wanted the political authorities rather than the schools to act as the regulatory body on smoking.Regulations issued by the county authorities appear to be a necessary, successful and welcome means of implementing a smoke-free environment in upper secondary schools.