In 1992, the Norwegian Medical Association started a comprehensive research programme on doctors' health and welfare. More than 30 studies are planned, based on a variety of data sets and methodologies. The core of the programme is the 1993 questionnaire survey. 9,266 active doctors received comprehensive questionnaires about their health, level of living and working conditions. The response rate was 72%. The response rate was higher for females than for males, 80% as against 69%. Of the categories of doctors, specialists in private practice showed the lowest response, 50%. In the main study a "question overlap" was applied, where each doctor received four out of 16 thematically different questionnaires. One questionnaire was common to all, the three others were randomly distributed among the recipients. The purpose of this design was to increase the potential for multivariate models in the analysis. We find the 72% response rate among the active doctors satisfactory, and feel confident that we have a reliable data base for further analyses.