Synthetic biology draws on the understanding from genetics, biology, chemistry, physics, engineering, and computational sciences to (re-)design and (re-)engineer biological functions. Here we address how synthetic biology can be possibly deployed to promote health and tackle disease. We discuss how drugs can be produced in more affordable ways, how new medicines can be developed, how the re-design of cellular pathways can correct endogenous malfunctioning in a series of diseases, how bacteria can be engineered to kill tumors, and how bacterial communities in the intestine can be modulated to restore gut homeostasis and prevent metabolic diseases. We indicate how new biomedical materials can be synthetized to replace tissues, how new biosensors can assist in diagnosis and prognosis, and how synthetic biology can help preventing the onset of disease in those cases in which until now only diagnosis was possible. On the basis of this, we discuss towards what directions synthetic biology in health and disease may develop in the future.