Understanding the potential profile of adverse events associated with cancer treatment is essential in balancing safety versus benefits. Multiple stakeholders make use of this information for decision making, including patients, clinicians, researchers, regulators, and payors. Currently, adverse events are reported by clinical research staff, yet evidence suggests that this may contribute to underreporting of symptom events. Direct patient reporting via electronic interfaces offers a promising mechanism to enhance the efficiency and precision of our current approach and may complement clinician reports of adverse events. The National Cancer Institute has contracted to develop and test an item bank and software system for directly eliciting adverse symptom event information from patients in cancer clinical research, called the Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events. The validity, usability, and scalability of the Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events prototype are currently being examined in academic and community-based settings.