Introduction: Participant interviews are often considered the ‘gold standard’ for measuring outcomes in diagnostic and prognostic studies. Participant exposure data are frequently collected during study interviews, but the reliability of this information often remains unknown. The objective of this study was to compare patient-reported medication exposures and outcomes to data extracted from electronic medical records (EMRs) to determine reliability. Methods: This was a secondary data analysis from a prospective observational cohort study enrolling older (≥ 65 years) patients who presented to one of three emergency departments after a fall. After patients had consented to participate in the study, they were asked about their use of antiplatelet and anticoagulation medications (exposures of interest). During follow up, participants were asked if a physician had told them they had bleeding in their head (diagnosis of intracranial hemorrhage). Patient-reported responses were compared to data extracted from a structured EMR review. Trained research assistants extracted medication exposure and outcome data from the hospital EMRs in duplicate for all visits to any hospital within 42 days. Inter-rater agreement was estimated using Cohen's kappa (K) statistics with 95% confidence intervals (CIs). Results: 1275 patients completed study interviews. 1163 (91%) responded to questioning about antiplatelet use and 1159 (91%) to anticoagulant use. Exact agreement between patient reported antiplatelet use compared to EMR review was 77%, with K = 0.50 (95% CI: 0.44 to 0.55). For anticoagulation use, exact agreement was 87%, with K = 0.68 (95% CI: 0.63 to 0.72). 986 (78%) patients had a follow up interview after 42 days. Exact agreement between patient reported intracranial bleeding and EMR review was 95%, with K = 0.30 (95% CI: 0.15 to 0.45). Using the EMR review as the reference standard, the sensitivity and specificity of patient reported intracranial bleeding was 34% (95% CI: 20 to 52%) and 97% (95% CI: 96 to 98%), respectively. Conclusion: In this population of older adults who presented to the ED after a fall, patient reported use of antiplatelet and anticoagulant medications was not a reliable method to identify medication use. Patients who were diagnosed with intracranial bleeding were particularly poor at reporting this diagnosis.