The incidence of sickness in general did not differ between permanent shift workers and day workers, but was highest in shift workers who transferred later to day work mostly for medical reasons Furthermore, on the average, shift workers were sick for longer periods than day workers.Significantly more shift workers than day workers consulted the occupational health services about gastrointestinal complaints than day workers. Shift workers had more frequent gastrointestinal diseases than day workers and more severe ones such as peptic ulcers Gastrointestinal diseases were more frequent in the following groups of the shift workers: Young ( 21 to 25 years) and unmarried subjects, heavy smokers and subjects with a past history of gastrointestinal diseases.No differences between shift workers and day workers could be detected concerning cardiovascular diseases including myocardial infarction Psychosomatic disorders were seldom diagnosed and did not differ between shift and day workers Surprisingly, skeletal diseases including the sequelae of accidents and injuries occurred more often in the shift workers' cohort; the possible cause of this was a higher incidence of moonlightning in shift workers or other activities beside work The need for prospective follow-up studies is emphasized.