Surgical flow disruptions can significantly increase the probability of surgical errors. However, little is known about the frequency and nature of surgical flow disruptions, making the development of evidencebased interventions extremely difficult. The goal of this project was to prospectively study surgical errors and their relationship to surgical flow disruptions within the context of cardiac surgery. A trained observer recorded surgical errors and flow disruptions during 31 cardiac operations over a three-week period. Flow disruptions were then reviewed and analyzed by an interdisciplinary team of surgical and human factors experts. Results revealed that flow disruptions consisted of teamwork/communication failures, equipment and technology problems, extraneous interruptions, training-related distractions, and resource accessibility issues. Errors increased significantly with increases in flow disruptions. Teamwork/communication failures were the strongest predictor of surgical errors. These findings provide preliminary data for developing evidenced-based error management and patient safety programs within cardiac surgery.