 The systematic review summarizes evidence on the impact of patient portals on health outcomes and health care efficiency, and examines user characteristics, attitudes, and satisfaction. The results show that patient portals have the potential to enhance the doctor-patient relationship, improve health status awareness, and increase adherence to therapy, but it is still unclear whether they improve health service utilization and efficiency. This article was authored by Electricorini, Leonardo Villani, Angelo Maria Pizzullo, and others.