Reports of interventions to improve adherence to medical regimens in solid organ transplant recipients are scarce. A systematic review identified 12 intervention studies. These studies focused on renal, heart, and liver transplant recipients. Five reports used randomized controlled trial (RCT) designs. Sample sizes varied between 18 and 110 subjects. The interventions are difficult to evaluate and categorize because of brief descriptions of intervention details. Of the 12 studies identified in this review, only five studies found a statistically significant improvement in at least one medication-adherence outcome with the intervention. In general, most included a combination of patient-focused cognitive/educational, counseling/behavioral, and psychologic/affective dimensions. Eight studies intervened at the healthcare provider, healthcare setting or healthcare system level, but showed a limited improvement in adherence. No single intervention proved to be superior at increasing medication-adherence in organ transplantation, but a combination of interventions in a team approach for the chronic disease management of organ transplant patients may be effective in a long-term perspective. In conclusion, finding the most effective combination of interventions to enhance adherence is vital. Utilizing an RCT design and adhering to the CONSORT guidelines can lead to higher quality studies and possibly more effective intervention studies to enhance medication-adherence.