The pathological and radiodiagnostic aspects of arthritis, bursitis, and allied conditions have been discussed in detail in the two preceding papers, by Drs. Angevine and Paul (pages 1 and 6). This presentation will relate our experience with the therapeutic use of roentgen rays in these conditions. Roentgen therapy of arthritis is by no means new; since the history of this particular field has been dealt with by several authors (4, 7), suffice it to say that as early as 1898 the subject was mentioned in the French, German, Russian, Swedish and Swiss literature (10). As far as we could ascertain the first American authors dealing with it were Anders, Daland and Pfahler (1), who published a preliminary report of the treatment of arthritis deformans with roentgen rays in 1906. Their results were encouraging and they reached the conclusion that this method is a valuable adjunct in the treatment of these chronic joint affections. In the literature of the last twenty years, however, there are not many references to roentgen therapy of arthritis. This is surprising if one considers the importance of the condition as well as its high incidence. Our report is rendered from a strictly practical standpoint and in an effort to induce more radiologists to try the method in a large number of cases so that we may eventually arrive at its true evaluation. Clinical Material During the four-year period 1941–45 we treated 331 separate cases of rheumatoid and hypertrophic arthritis. Early in 1945 we decided to accept as many cases as possible for the present study. All patients were examined in the diagnostic section of our department and the extent of arthritic involvement was graded. One hundred consecutive cases of arthritis and allied diseases were taken from those treated that year. The results could thus be observed and recorded by the same physician, although it obviated the study of duration of response. This group of patients is heterogeneous, consisting of state, clinic, and private cases, rural and urban. There was, however, a predominance of farmers, explaining the large number of severe cases of hypertrophic arthritis, a disease which appears to be aggravated by a lifetime of hard work. Ages were well spaced from forty to eighty years, the decade of sixty to seventy having the largest representation. All patients were seen by a member of another department, and many of them were sent to us by the Department of Orthopedic Surgery. All were interviewed by a member of the therapeutic section of our department and the extent of disability was recorded. No objective study was attempted except the taking of roentgenograms in all cases. About 70 per cent of the group were followed by personal interviews; the remainder by mail. Ninety-two cases were traced. Technic While in general we do not believe in standardized technic for anyone disease, yet most of our cases received essentially the same amount of therapy.