Medical team training (MTT) has been touted as a way to improve teamwork and patient safety in the operating room (OR). OR personal completed a 1-day intensive MTT training. A standardized briefing/debriefing/perioperative routine was developed, including documentation of OR miscues, delays, and a case score (1-5) assigned by the OR team. A multidisciplinary MTT committee reviewed and rectified any systems problems identified. Debriefing items were analyzed comparing baseline data with 12 and 24-month follow-up. A safety attitudes questionnaire was administered at baseline and 1 year. A total of 4863 MTT debriefings were analyzed. One year following MTT, case delays decreased (23% to 10%, P < 0.0001), mean case score increased (4.07-4.87, P < 0.0005), and both changes were sustained at 24 months. One-year and 24-month follow-up data demonstrated decreased frequency of preoperative delays (16%-7%, P = 0.004), hand-off issues (5.4%-0.3%, P < 0.0001), equipment issues/delays (24%-7%, P < 0.0001), cases with low (<3) case scores (23%-3%, P < 0.0005), and adherence to timing guidelines for prophylactic antibiotic administration improved (85%-97%, P < 0.0001). Surveys documented perception of improved teamwork and patient safety. A major systems issue regarding perioperative medication orders was identified and corrected. MTT produced sustained improvement in OR team function, including decreased delays and improved case scores. When combined with a high-level debriefing/problem-solving process, MTT can be a foundation for improving OR performance. This is the largest case analysis of MTT and one of the few to document an impact of MTT on objective measures of operating room function and patient safety.