The apparent fall of rheumatic fever incidence in developed countries and in Yugoslavia is one of the reasons of negligence of the diagnosis of this disease. This fall was associated with mild forms of rheumatic fever (arthritis and mild forms of carditis are the main manifestations) where the beginning resembled other rheumatic disease. Consequently the problem of diagnosis of rheumatic fever is complicated. The early diagnosis of rheumatic fever is very important for the course of the disease, because appropriate measures (secondary prophylaxis) can prevent recurrence and severe rheumatic heart defects. The other disease recent increase of rheumatic fever incidence in the United States is the warning to other countries.