This study examined the effect of implementing a new preoperative briefing protocol on self- and peer-assessments of individual operating room (OR) teamwork behaviors. From July 2006 to February 2007, OR teamwork performance at a rural community hospital was evaluated before and after training and implementation of the protocol. After each case, every member on the team completed a 360-degree type teamwork behavior evaluation containing both self- and peer-assessments using a six-point Likert type scale (1 = definitely no to 6 = definitely yes). Individual behavior change was measured using the mean scale score of pre and postprotocol assessments. Statistical analysis included t test for both pre/post and self/peer differences. Data were available for one general surgeon and nine OR staff (pre = 20 cases, post = 16 cases). The preprotocol self-assessment mean score was significantly higher than peer-assessment (5.63 vs 5.29, P < 0.0267). Pre and postprotocol peer assessment mean scores revealed a statistically significant gain in teamwork behaviors. No difference was observed in postassessment mean scores for self- and peer-assessments. Individuals overestimated their teamwork behaviors before protocol implementation. Using a preoperative protocol seems to improve OR staff teamwork behaviors and self-assessment accuracy. The use of a 360-degree assessment method targeting specific, observable behaviors may be useful in evaluating team-based interventions and enhancing teamwork effectiveness.