Poor adherence to medication is a persistent problem in the practice of medicine, which gives rise to problems for individual patients, for the healthcare system as a whole, and in some cases, for third parties and for public health. There has been some progress in understanding the causes and solutions but much more work needs to be done. To develop the ethical responses to adherence, the problems need to be analysed more precisely. It is argued that, given that one pressing (...) concern is whether poorly adherent patients are being unfairly blamed or stigmatised, it is necessary to pay attention not just to the content of claims about adherence, but to the rhetoric of how these are presented. A necessity-concerns framework does much to advance understanding and ethics but may have certain pitfalls, and an approach based on micro-economic modelling may help to refine understandings of the position of the patient. It is also argued that a more sophisticated understanding of the ethical issues will be gained by recognising two problems: first, poor adherence to medications per se; second, poor knowledge about adherence to medications. These are related, but give rise to distinct ethical concerns. (shrink)