The role played by the health commissions in preventive health work in a major and a minor urban community in Telemark, Skien and Langesund respectively, is analysed by means of a classification method applicable to cases and decisions referred to in the proceedings of the health commissions. Increasingly, health commissions had to rely on their own initiative under the leadership of the district medical officer. After 1890, the decisions reached by the health commissions were increasingly recommendations to local authorities. Sanitation and waste processing were the principal problems. Regular house-to-house inspections in Langesund appear to have become effective, while the problems in Skien presumably were too great to permit similar improvements there. Even though practical work of preventing the spread of epidemic diseases had to remain the doctors' responsibility, the health commissions were active in providing the necessary resources. However, the commissions did not play a leading role in developing improved drinking water supplies or other major issues essential to health. Neither did they engage to any considerable extent in the distribution of public health information. On the other hand, the commissions acted as a controlling authority in cases brought before them, thus fulfilling the intentions of the Health Act of 1860.