Medical cannabis is widely available in the USA and legalisation is likely to expand. Despite the increased accessibility and use of medical cannabis, physicians have significant knowledge gaps regarding evidence of clinical benefits and potential harms. We argue that primary care providers have an ethical obligation to develop competency to provide cannabis to appropriate patients. Furthermore, specific ethical considerations should guide the recommendation of medical cannabis. In many cases, these ethical considerations are extensions of well-established principles of beneficence and nonmaleficence, which indicate that providers should recommend cannabis only for conditions that have the strongest evidence base. Additionally, the contested status of cannabis in American culture raises specific issues related to shared decision-making and patient education, as well as continuing clinical education.