Psychosomatic medicine, with its prevailing biopsychosocial model, aims to integrate human and exact sciences with their divergent conceptual models. Therefore, its own conceptual foundations, which often remain implicit and unknown, may be critically relevant. We defend the thesis that choosing between different metaphysical views on the ‘mind–body problem’ may have important implications for the conceptual foundations of psychosomatic medicine, and therefore potentially also for its methods, scientific status and relationship with the scientific disciplines it aims to integrate: biomedical sciences, psychology (...) and social sciences. To make this point, we introduce three key positions in the philosophical ‘mind–body’ debate and investigate their consequences for the conceptual basis of the biopsychosocial model in general and its ‘psycho-biological’ part in particular. Despite the clinical merits of the biopsychosocial model, we submit that it is conceptually underdeveloped or even flawed, which may hamper its use as a proper scientific model. (shrink)