Background. Despite high efficacy rates for direct acting antiviral regimens to cure hepatitis C virus infection, many patients experience treatment-related symptoms. Accurate reporting of adverse events is mandatory to determine drug safety. Previous research in other medical conditions has documented discordance between clinician-reported and patient-reported symptomatic adverse events. Aims. To explore concordance and associated factors, between clinician-recorded and patient-reported fatigue, headache, and nausea/vomiting during a clinical trial of three treatment regimens. Methods. Data were collected between treatment start and 31 days posttreatment. Patients completed Patient-Reported Outcomes Measurement Information System measures of fatigue and nausea/vomiting and the Headache Impact Test. Clinician-recorded data were abstracted from medical records. Concordance was evaluated by weighted kappa. Demographic and clinical factors associated with concordance were identified using logistic regression models. Results. Participants included 1,058 patients treated for chronic hepatitis C (average 54.9 years; 43% Black; 59% male). Weighted kappa estimates and 95% confidence intervals between patients (no/mild vs. moderate/severe symptoms) and clinicians (not present vs. present) were fatigue ( k = 0.09 , 0.02-0.16), headache ( k = 0.08 , 0.02-0.14), and nausea/vomiting ( k = 0.20 , 0.11-0.28). Older age and having private insurance (compared to Medicaid) were associated with better headache concordance. Older age, male, absence of psychiatric condition, and ≤2 comorbidities were associated with better nausea/vomiting concordance. Conclusions. Poor concordance was observed between patient-reported and clinician-recorded symptomatic adverse events. Despite study limitations, previous literature in other conditions support these findings. Integrating patient-reported data to inform adverse event reporting would improve evaluations of treatment safety (http://CT.gov/ Registration: NCT02786537).