Data are presented to illustrate the inadequacy of routinely collected data on osteoarthrosis when disability and handicap are considered as distinct from impairment. In a series of prevalence studies of mixed manual workers aged 15 to 65 years in the United Kingdom 11% had diagnosable osteoarthrosis of the limbs, 2% had generalized osteoarthrosis, and 11% had vague pains of undetermined diagnosis in the limb joints. Annual sickness absence was 580 d/100 affected men for those with local osteoarthrosis and 539 d/100 and 80 d/100, respectively, for those with generalized osteoarthrosis and vague limb pain. These and other indicators of disablement (hospital attendance and admission, self therapy, and consultation with general practitioners) suggest that osteoarthrosis makes a significant contribution to the handicap of manual workers. There was no significant difference in the prevalence rates between skilled and unskilled dockyard workers; this finding contrasts with the significantly higher rates for osteoarthrosis at all ages among coal miners working in awkward postures in confined spaces than among weight-lifting manual workers in other occupations. Direct observation and assessment of specific tasks support the hypothesis that posture may be more important than weight lifting as a risk factor in the onset of osteoarthrosis.