An examination was made of relationships between the physical health and mental depression of nurse shiftworkers and their scores on relevant social and work-related variables. Nurses on the day, afternoon, night and rotating shifts from five hospitals (n = 463) were surveyed using a mail-back questionnaire. Two alternative models were examined in the study. The first model suggests that shift work influences the physical health and mental depression of nurses, which in turn affect social and work-related variables including: family relations; formal and informal social participation; solitary activities; job performance; and job-related stress. Shiftwork's disturbance of the body's circadian rhythm would exert a direct affect on nurses' physical health and mental depression, which in turn would then affect other aspects of the nurses' lives. The second model suggests instead that shift work primarily affects social and work-related variables, which then influence physical health and mental depression. Circadian rhythm desynchronization, while still being a consequence of shiftwork, might not directly affect physical health and mental depression. Contrary to either of the two models proposed for the study, shiftwork was not found to be significantly related to either the nurses' physical health or mental depression. However, certain factors, when considered in conjunction with the unique shift-related job characteristics of nursing, may help to explain the study's unexpected findings.