This is the fifth edition of the Primer on the Rheumatic Diseases, previous editions having been published in 1934, 1942, 1949, and 1953. This publication presents basic material concerning rheumatic diseases in as simple and concise a form as is consistent with adequate coverage, bearing in mind the particular needs of the general physician and the student. The voluminous and rapidly expanding literature is not cited because of the condensed nature of the primer. The 12th "Review of American and English Literature," the previous "Reviews," and textbooks by outstanding authorities in the field are available in medical libraries for more extensive reading and background. The new journalArthritis and Rheumatism, now the official organ of the American Rheumatism Association, and theAnnals of the Rheumatic Diseases, published in London, provide the clinician with an abundant source of current articles on these subjects. The terms "rheumatism" and "rheumatic diseases" are now