The problem of undermedication of pain in health care is widely recognized and acknowledged; however, there is an obvious lack of exploration of this problem from an ethical perspective. When undermedication is raised as a moral concern, the underlying premise is that a patient may experience harm or not benefit from ineffective pain management practices. I will argue that the harm is of a particular type, that is, moral negligence. My intention is to increase nurses' awareness of both the type of moral harm they are causing, and their professional and moral duties to provide appropriate medication, more particularly to avoid undermedication. I hope that this heightened awareness will be incorporated into practice. As a nurse, I chose to focus on nursing for this article, but my claims are applicable to other health professions, such as medicine.