Patient-reported outcome (PRO) questionnaires assess topics a patient can report about his or her own health. This includes symptoms (eg, nausea, fatigue, diarrhea, pain, or frequent urination), physical functioning (eg, difficulty climbing stairs or difficulty fastening buttons), and mental health (eg, anxiety, fear, or worry). Electronic PRO (ePRO) systems are used in oncology clinical care because of 1) their ability to enhance clinical care by flagging important symptoms and saving clinicians time; 2) the availability of standardized methods for creating and implementing PROs in clinics; and 3) the existence of user-friendly platforms for patient self-reporting like tablet computers and automated telephone surveys. Many ePRO systems can provide actionable links to clinical care such as summary reports in a patient's electronic medical record and real-time e-mail alerts to providers when patients report acute needs. This review presents 5 examples of ePRO systems currently in use in oncology practice. These systems support multiple clinical activities, including assessment of symptoms and toxicities related to chemotherapy and radiation, postoperative surveillance, and symptom management during palliative care and hospice. Patient self-reporting is possible both at clinical visits and between visits over the Internet or by telephone. The implementation of an ePRO system requires significant resources and expertise, as well as user training. ePRO systems enable regular monitoring of patient symptoms, function, and needs, and can enhance the efficiency and quality of care as well as communication with patients. CA Cancer J Clin 2012. © 2012 American Cancer Society.