The Agency for Healthcare Research and Quality (AHRQ) recommends assessing employees' perception of the culture of safety on their unit in order to target patient safety efforts. In this study, the investigators surveyed personnel of four intensive care units at a single hospital using the Safety Attitudes Questionnaire, which evaluates perceptions of teamwork climate, stress recognition, and management commitment to safety. The perception of safety culture varied widely across units and across all domains of the survey. As found in prior research, nurses had a more negative impression of the safety culture than did physicians or managers. The authors conclude that analysis of safety culture at the institutional level may result in misleading impressions.