In 1987 and 1988 treatment programmes prepared by general practitioners were sent to the 2,900 doctors working in primary health care in Norway. In March 1990 a random sample (n = 600) were sent a questionnaire. The response rate was 63%. The general practitioners were greatly in favour of such programmes. 80% had read the programmes fully or in part, and one third used them regularly (at least once a month). Young doctors with little experience used them most and reported greatest benefit from the programmes. Reading and use of the programmes were strongly associated with participation in meetings and courses where the programmes had been used, and also with whether the general practitioners had used them for teaching the staff in their practices. 40% of the doctors who had received the programmes reported changes in their practice. Most of the changes referred to the doctors' own treatment routines, and less to areas requiring organizational changes in their practices. The general practitioners also answered questions on a test case with type 2 diabetes. 80% answered in accordance with the diabetes programme. The answers of those who had read and used the programme complied best with its recommendations.