Nurses' fear of contagion when caring for persons with AIDS remains high despite increased levels of knowledge. This paper examines the multiple factors that contribute to nurses' perception of risk within the workplace. The authors suggests that constructs from theories such as decision making, psychoanalysis and cognitive psychology can provide insight into the assessment of risk. Findings from a recent survey of nurses are used to illustrate the complex nature of fear of contagion. Understanding this complexity may be an essential first step in order to provide opportunities for resolution of fears and modification of behaviors.