The purpose of this research was to examine the influence of day, afternoon, night and rotating shift schedules on the job performance and job-related stress of nurses. Registered nurses from five hospitals (n = 463) were surveyed using a structured questionnaire which measured both job performance and job-related stress. Analysis of data indicated that both the nurses' job performance and their job-related stress were related to the type of shift they worked. Overall job performance was highest for the nurses on the day shift, followed by the night, afternoon, and rotating shifts. Rotating shift nurses experienced the most job-related stress, followed in turn by the afternoon, day, and night shift nurses. The findings are interpreted within a conceptual framework which examines the social organization of work in the hospital by shift and the effects of shift work on biological rhythm synchronization.