Relapsing polychondritis (RP) is not a totally rare rheumatic disease. We have seen 23 patients from 1960-1975, and there are now a total of 159 reported cases, which form the basis of this study. RP occurs equally in both sexes, and has a maximum frequency in the fourth decade. 2) Empirically defined diagnostic criteria are proposed, to include the most common clinical features: a) Bilateral auricular chondritis b) Nonerosive sero-negative inflammatory polyarthritis c) nasal chondritis d) Ocular inflammation e) Respiratory tract chondritis f) Audiovestibular damage The diagnosis is based primarly upon the unique clinical features, and is quite certain if three or more criteria are present together with histologic confirmation. 3) Fifty percent of patients present with either auricular chondritis or the arthropathy of RP; but with prolonged follow-up, a majority of patients develop four or more of the above mentioned criteria. 4) Approximately 30 percent of patients have a preceding or coexistent rheumatic or autoimmune disease, which can lead to initial diagnostic confusion. 5) Laboratory and radiographic investigations help mainly to rule out other diagnostic possibilities, with no characteristic abnormalities being present in a majority of patients. 6) On follow-up, three-fourths of our patients required chronic corticosteroid therapy with an average dose of 25 mg per day of prednisone. Corticosteroids decrease the frequency, duration, and severity of flares, but do not stop disease progression in severe cases. 7) The mortality rate has been 30 percent in our series and 22 percent in the other 136 reported cases. Of the 29 cases where the cause of death was known, 17 were from respiratory tract involvement and 9 from cardiac valvular or vasculitic involvement, emphasizing the need to search for critical involvement of either of these organ systems in each patient. 8) Detailed reports of selected cases are presented to illustrate the clinical diagnosis and differential diagnosis, and to demonstrate the need for careful prolonged follow-up. 9) Although the etiology remains unknown, there is a frequent association with, and clinical similarity to, other rheumatic diseases. 10) Careful clinicopathological study of our 23 patients leads us to postulate an underying systemic vascultis as an important pathologic mechanism in RP.