The work activities of nurses working in hospitals were characterized in order to determine those actions which are frequent and likely to contribute to back pain. Several hospital units participated in an observational study of the work activities of nurses, including intensive care, medical and surgical, recovery room and delivery room among others. Eighty percent of the nurses studied were female and the subjects had a mean age of 31.2 years. The activities observed included all nursing activities other than clerical duties. Actions were characterized as to whether patient contact was involved and whether the activity was dynamic or static. Sixty three work shifts were observed. Patient contact actions involving motion, most of which concerned helping patients to move in bed, were more frequent than static actions. Nonpatient contact actions, which often involved manipulating equipment and heavy objects, were more frequent than patient contact activities. All static actions were, by definition, patient related. The majority of these actions were performed in squat positions, possibly increasing low back stress. The authors conclude that a broad range of physical activities could contribute to low back stressor exposures of hospital nurses. They suggest that work practice training programs should be expanded to methods for dealing safely with all types of activities and not focus only on patient transfer activities.