Biochemical tests (serum calcium, inorganic phosphate and alkaline phosphatase), as well as clinical, radiological, scanning and histological investigations were undertaken in 24 patients in chronic renal failure. The frequency with which the diagnosis of renal osteopathy could be made depended in the method of investigation, the biochemical findings proving to be completely unreliable. There were positive radiological signs in ten patients and clinical signs in 12, predominantly in the progressive stages of osteopathy. A positive scan was obtained in 23 patients, typical histological bone changes in an equal number. Since it correlates so well with the histological findings, bone scan is suitable particularly in the early diagnosis of osteopathy. Since this test is easily performed and hardly stresses the patient, it should routinely be the initial one for the diagnosis of renal osteopathy.