Nonadherence to immunosuppressant therapy constitutes a major barrier to post-transplant care. Failure of transplant recipients to take prescribed drugs properly may not only be a significant obstacle to optimal graft function but it may also result in decreased quality of life and productivity, increased morbidity and healthcare cost, and death. Despite the obvious importance of adherence to immunosuppressant therapy, nonadherence is frequent among transplant recipients, with rates ranging from 2 to 68%. This manuscript briefly discusses several issues concerning adherence to immunosuppressant therapy of solid-organ transplant recipients; presents a literature review concerning adherence to immunosuppressant therapy by solid-organ transplant recipients; and suggests strategies that may be used to enhance medication adherence. Although many of the studies have results that conflict concerning factors associated with immunosuppressive nonadherence, most of the investigators concluded that nonadherent behaviour is usually not predictable. Because of possible adverse events, emphasis should be placed on increasing medication adherence in all transplant recipients.