From 1924 and onwards, obligatory tuberculin test (Pirquet's method) was introduced at the time when student nurses commenced their training at Ullevål Hospital's school of nursing. Chief physician of the hospital's department IX, Olaf Scheel, was responsible for this measure. In 1927, his deputy, Johannes Heimbeck, showed that about half of the students were not infected at the time of school entrance. This conclusion was in fundamental conflict with the prevailing view that nearly all tuberculous infection took place in childhood. Virtually all Pirquet-negative student nurses were, however, infected in the course of the three-year training period. BCG vaccine had recently been introduced by Calmette. From 1927 onwards, Heimbeck offered BCG vaccination to the Pirquet-negative student nurses, while Scheel undertook a similar project among medical students. The two projects went on to 1936 and 1939. Follow up of both groups demonstrated a protective effect of about 80 per cent. Calmette had given the vaccine per os to new-born babies. Heimbeck and Scheel pioneered by giving the vaccine by injection and to adults. The projects have been criticised for being based on voluntary attendance and not conducted as randomised control trials. The results, however, were so convincing that they became decisive for the Norwegian BCG programme that was launched shortly after the Second World War. The efforts by Scheel and Heimbeck were also of great importance to the use of BCG vaccine in other countries.