Background: The operating room (OR) is an important venue where surgeons do much of medical student teaching and yet there has been little work evaluating variables that influence learning in this unique environment. We designed this study to identify variables that affected medical student learning in the OR. Methods: We developed a questionnaire based on surgery faculty observations of learning in the OR. The medical students completed the questionnaire on 114 learning episodes in the OR. Pearson correlation coefficient was used to establish the strength of association between various variables and the student's overall perception of learning. Results: The students evaluated 27 variables that might impact their learning in the OR. Strong correlations were identified between the attending physician's attitude, interactions and teaching ability in the OR and the environment being conducive to learning. Conclusions: Surgical faculty behavior is a powerful determinant of student perceptions of what provides for a favorable learning environment in the OR. © 2004 Excerpta Medica, Inc. All rights reserved.