Cancer pain relief has been defined as a worldwide public health challenge in the last decades and has recently been included in public debates as a human rights issue. However, barriers to the provision of adequate pain management continue to exist. This article analyzes the cancer pain treatment provided in a palliative care setting in the Autonomous City of Buenos Aires, focusing on how professionals and patients implement and negotiate the terms and adherence to the pain treatment. Based on a qualitative approach that triangulates data from semi-structured interviews and from ethnographic observations, the article addresses the way pain is measured and assessed and the strategies of health professionals in establishing pain treatment protocols. The article also describes the rhetoric regarding the right to pain relief developed by health professionals through their practice and discusses the limitations of that rhetoric.