After discussing some important alternative approaches, different interpretations are presented of the concepts of health, disease, diagnosis, therapy and patient. These differences are elucidated in three main frames of medical thinking: the pharmaceutical, the integrational and the holistic model. Attention is given to the problem of scientific proof, especially in relation to the effectiveness of alternative therapies. In a concluding paragraph it is attempted to analyse the (social) backgrounds of the controversy between regular and alternative medicine.