During 1980, 1153 employees attended the Occupational Health Department with back pain out of a working population of 13,958 in a car factory. Of these, 401 were absent from work and a further 64 patients were restricted by back pain and unable to perform their normal work; 147 cases of back pain arose at work, and 71 in and around the home. All those who were absent or restricted were questioned about the onset of back pain in order to distinguish between accidental and nonaccidental injuries (NAI), and an accident model was used to structure the information. There were 122 accidents, 114 NAI, and 165 patients who could not attribute a cause to their back pain. A significantly higher proportion of the NAI arose at home and, conversely, a higher proportion of accidents occurred at work. Of the accidents, 80 (66%) were underfoot accidents, including 57 slips. There were highly significant differences between the body movements contributing to accidents and NAI. Significantly more of the NAI than the accidents involved load handling, but 52% of the patients able to attribute a cause to their back pain were not moving loads. While handling of loads is important, attention should be directed to other contributory factors such as unsafe floor surfaces and bending and twisting movements-not only at work but also in and around the home.