The purpose of this study, a component of a randomized clinical trial, was to assess the influence of the emergency department environment and participant characteristics on the accuracy of self-reported health care utilization. Interviews of 612 seniors aged 65 to 93 were conducted in two emergency departments. The research assistant, upon completion of each interview, rated characteristics of the emergency department and compared participants' self-reports of emergency department use and hospitalization during the previous 4 weeks with data from hospital records: 3.6% overreported and 2.2% underreported visits to the emergency department. Regarding hospitalizations, 2.6% overreported and 1.2% underreported. Discrepancies were associated with male gender, cognitive deficits, and risk status. Inconsistencies were not related to any of the environmental variables. These findings suggest that seniors without cognitive decline report reliable data even in a potentially challenging environment.