On the basis of well defined diagnostic criteria, the authors conclude that periodic disease affects males in particular. It commences before the age of 20 years in 80 percent of cases. In particular it occurs in Armenian and Shiite communities. Its evolution is normally benign ; amyloidosis is found in only 8 percent of cases. Joint manifestations are found in 48 percent of cases and may take on different aspects and occur in several different sites : myaglia or arthralgia, monoarthitis, oligoarthritis, polyarthritis, neck or sacroiliac pain. The authors have not noted prolonged peripheral joint episodes. No cases of amyloidosis were diagnosed before the appearance of the clinical signs of the disease. An autosomal, dominant heredity with incomplete penetration seems to be the most likely hypothesis.