BACKGROUND: The Quality and Costs of Primary Care in Europe (QUALICOPC) study aims to analyse and compare how primary health care systems in 35 countries perform in terms of quality, costs and equity. This article answers the question 'How can the organisation and delivery of primary health care and its outcomes be measured through surveys of general practitioners (GPs) and patients?' It will also deal with the process of pooling questions and the subsequent development and application of exclusion criteria to arrive at a set of appropriate questions for a broad international comparative study. METHODS: The development of the questionnaires consisted of four phases: a search for existing validated questionnaires, the classification and selection of relevant questions, shortening of the questionnaires in three consensus rounds and the pilot survey. Consensus was reached on the basis of exclusion criteria (e.g. the applicability for international comparison). Based on the pilot survey, comprehensibility increased and the number of questions was further restricted, as the questionnaires were too long. RESULTS: Four questionnaires were developed: one for GPs, one for patients about their experiences with their GP, another for patients about what they consider important, and a practice questionnaire. The GP questionnaire mainly focused on the structural aspects (e.g. economic conditions) and care processes (e.g. comprehensiveness of services of primary care). The patient experiences questionnaire focused on the care processes and outcomes (e.g. how do patients experience access to care?). The questionnaire about what patients consider important was complementary to the experiences questionnaire, as it enabled weighing the answers from the latter. Finally, the practice questionnaire included questions on practice characteristics. DISCUSSION: The QUALICOPC researchers have developed four questionnaires to characterise the organisation and delivery of primary health care and to compare and analyse the outcomes. Data collected with these instruments will allow us not only to show in detail the variation in process and outcomes of primary health care, but also to explain the differences from features of the (primary) health care system.