OBJECTIVE: To evaluate Universal Precautions (UP) compliance in the operating room (OR). DESIGN: Prospective observational cohort. Trained observers recorded information about (1) personal protective equipment used by OR staff; (2) eyewear, glove, or gown breaks; (3) the nature of sharps transfers; (4) risk-taking behaviors of the OR staff; and (5) needlestick injuries and other blood and body-fluid exposures. SETTING: Barnes-Jewish Hospital, a 1,000-bed, tertiary-care hospital affiliated with Washington University School of Medicine, St Louis, Missouri. PARTICIPANTS: OR personnel in four surgical specialties (gynecologic, orthopedic, cardiothoracic, and general). Procedures eligible for the study were selected randomly. Hand surgery and procedures requiring no or a very small incision (eg, arthroscopy, laparoscopy) were excluded. RESULTS: A total of 597 healthcare workers' procedures were observed in 76 surgical cases (200 hours). Of the 597 healthcare workers, 32% wore regular glasses, and 24% used no eye protection. Scrub nurses and medical students were more likely than other healthcare workers to wear goggles. Only 28% of healthcare workers double gloved, with orthopedic surgery personnel being the most compliant. Sharps passages were not announced in 91% of the surgical procedures. In 65 cases (86%), sharps were adjusted manually. Three percutaneous and 14 cutaneous exposures occurred, for a total exposure rate of 22%. CONCLUSION: OR personnel had poor compliance with UP. Although there was significant variation in use of personal protective equipment between groups, the total exposure rate was high (22%), indicating the need for further training and rein-forcement of UP to reduce occupational exposures.