Various occupations were studied for the prediction of herniated lumbar intervertebral disc or sciatica in 592 men and women who had been discharged from hospital with these diagnoses during an 11-year follow-up after a health examination. The cases were compared with 2140 controls matched individually for sex, age and place of residence. Subjects who, at the initial examination before the follow-up, had reported a history of back pain or sciatica were excluded. In men, the risk of being hospitalized due to herniated lumbar disc or sciatica was lowest in professional and related occupations, significantly higher in all other groups and highest among blue-collar workers in industry and among motor vehicle drivers. The variation in the risk between occupational groups of women proved less but was nevertheless still apparent. However, in women, but not in men, the risk was significantly associated with self-assessed strenuousness of work.