Between 1952 and 1980 about 250 patients with ankylosing spondylitis were treated with /sup 224/Ra at the Orthopaedic University Hospital of Frankfurt/M. In 1970, 119 of them were examined and X-rayed as was another group of 40 patients in 1980. The results of those examined could be compared with a group of 40 patients treated without /sup 224/Ra. Patients with /sup 224/Ra demonstrated a long-lasting period of subjective improvement after the treatment, with reduced consumption of antirheumatoid and analgesic drugs, on the average. Blood examinations show inflammatory activities. Nevertheless, the ankylosing spondylitis proceeded. In the final stages of the disease, neither the clinical aspects nor the X-rays showed any specific changes. We observed no case of malignant bone tumor. Of the 169 examined patients, 22 had a total of 32 children after the treatment with /sup 224/Ra. Among these was a set of twins with cerebral palsy and diabetes insipidus renalis. In conclusion, /sup 224/Ra in ankylosing spondylitis is a recommended treatment without higher risk compared to the common therapy with drugs.