224Ra is used within the therapy of rheumatoid arthritis. The distribution of this radionuclide in the organism was investigated up to 7 days after incorporation in order to estimate a possible risk of late effects. In the autoradiographs we found strong blackenings at those bone surfaces which faced the injected knee-joint hole. In addition the radionuclide was deposited in skeletal growth-zones similarly as after i.v. and i.p. injections. The dosimetric data (particularly of knee-joint and skeleton) were calculated and compared with those which occur after the therapy of ankylosing spondylitis using i.v. 224Ra injections.