Medicolegal realities surrounding "medical marijuana" or "medical cannabis" are rapidly evolving in the United States. Clinicians are increasingly being asked by patients to share information about or certify them for medical cannabis. In order to engage in informed discussions with patients or be comfortable certifying them in states with medical cannabis laws, clinicians may benefit from an understanding of the current state of medical knowledge about medical cannabis. Intended for the generalist and subspecialist, this review provides an overview of the legal status, pharmacology, benefits, risks, and abuse liability of medical cannabis along with a general framework for counseling patients.