Homeopathy relies on two basic tenets: the simile principle and the potentisation procedure. The validity of these presumptions is being questioned since there seems to be no obvious scientific basis supporting justifiable application in pharmacy and medicine. Nevertheless, homeopathy is being practised and many patients as well as practitioners are quite satisfied with clinical outcome in daily practice. However, the lacking understanding does lead not only to problems with legal recognition, integration into public healthcare and reimbursement by health insurances, but also hampers further development and optimisation of homeopathic therapy. Therefore, development of a deeper understanding of the two basic tenets of homeopathy is of ultimate importance.