Errors with serious consequences continue to occur at a high rate in many surgical specialties. In this study, the Human Factors Analysis and Classification System (Wiegmann & Shappell, 2003) was used to develop a structured interviewing tool for prospectively assessing the systemic factors that may predispose operating room (OR) personnel to making errors. Approximately 50% (n = 68) of all staff involved in patient care within the cardiac surgery OR at our institution participated, with an equal proportion represented across staff specialties (Surgeons, Anesthesiologists, Nurses, Perfusionists and Technicians). Results identified a variety of potential error-producing factors present in the OR setting. While such factors were viewed by OR staff as occurring infrequently, significant relationships between the estimated frequency of systemic problems and specific error forms were identified. These findings can inform both the development of theoretical models of surgical error, as well as the practice of developing targeted intervention programs.