Although some studies have suggested that osteoporosis and osteoarthritis are inversely related in epidemiologic terms, a spectrum of relations between the two diseases has been described in this study. In 95 postmenopausal women (mean age 64.4 +/- 8.49 years, range 49-83 years), we investigated the relation between bone mineral density (BMD) in the femoral neck and lumbar vertebrae (L2-L4) and osteoarthritis in the knee. BMD was measured with dual X-ray absorptiometry. Osteoarthritis was evaluated with anterior-posterior weight-bearing radiographs with the knee in extension, and these were graded for severity on a 5-point scale according to the Kellgren-Lawrence criteria. We found no clear statistical relation between BMD in the femoral neck or lumbar vertebrae and osteoarthritis in the knee. Given that some studies have found BMD to be significantly higher in patients with osteoarthritis, the lack of such relation in our patients may be due to environmental and/or genetic factors.