Abstract Background Surgical site infections (SSIs) complicate nearly 6% of surgeries performed in Veterans Health Administration (VA) hospitals and occur despite adoption of practices known to reduce them. SSIs are associated with prolonged hospitalization and an increased risk of readmission, reoperation and mortality. Operating room (OR) door openings may increase SSI through disruption of desired OR air flow patterns and increased wound microbe counts. Our study objectives were to: 1) develop a methodological approach for collecting data on entry/exit traffic patterns in VA ORs and 2) characterize patterns across different surgery types. ...