A radiological study of osteoarthrosis of the hips and knees has been performed in 364 female specialist physical education teachers, aged 46--60 years, who qualified between the years 1935 and 1950. The teachers were contacted by postal questionnaire and A.P. radiographs of the pelvis and knees were performed at a hospital in their residential locality. These were then read by two rheumatologists in consultation and graded for osteoarthrosis by comparison with the Atlas of Standard Radiographs. These gradings were compared with those of similarly aged females in the general population obtained in the Leigh and Wensleydale surveys. Moderate and severe osteoarthrosis of the knees was equally common in the teachers and the general population but minimal and mild osteoarthrosis was significantly less common in the teachers (p less than 0.001). Osteoarthrosis of the hips was more common in the teachers than in the population, though not to a statistically significant degree. An association was noted in the teachers between osteoarthrosis of the hips and ossification in the region of the greater trochanter. The results suggest that female physical education teachers are no more prone to the development of premature osteoarthrosis of the hips and knees than is the general population, but there may be a subgroup who, because of excess use of hypermobility of the hip joints, develop osteoarthrosis as a consequence.