The authors examined the association of hip osteoarthritis with the presence of Heberden's nodes in a case-control study. Subjects were men aged 60-75 years who had undergone intravenous urography as out-patients. An examination of the hands was carried out in 240 patients who had a hip replacement for osteoarthritis or a joint space less than or equal to 2.5 mm, and in 290 controls whose joint space was greater than or equal to 3.5 mm in both hips. The presence of Heberden's nodes was associated with an increased risk of radiological hip osteoarthritis, the relationship being stronger in the 51 cases with severe joint-space narrowing (odds ratio = 3.4, 95% confidence interval 1.3-9.1). There was no evidence that this association differed according to the site of joint space narrowing within the hip. The finding provides further evidence that osteoarthritis of the hip can occur as part of a generalized process and does not only result from local damage to the joints.