OBJECTIVE The incidence of acute rheumatic fever (ARF) in the United States and Western Europe is decreasing and postStreptococcal reactive arthritis (PSRA) is more prevalent. It is not clear whether PSRA is a forme fruste of ARF or a separate disease entity. Therefore, this review explores similarities and dissimilarities in initial symptoms and signs, disease course and underlying pathophysiologic mechanisms. RESULTS ARF and PSRA present differently. PSRA patients are generally older, have a longer interval between group A streptococcus infection and symptom onset, and respond less dramatically to salicylates than ARF patients. The course of ARF may be complicated by carditis and valvular heart disease. Echocardiographic studies in Caucasian adults with PSRA have revealed no increase in valvular heart disease. The course of PSRA is characterized by arthritis that, in contrast to ARF, is additive, nonmigratory and is frequently chronic. Factors of the host, the Streptococcus and the immune response involved in the development of PSRA are scarcely explored, hampering comparisons with ARF. CONCLUSIONS On the basis of the differences in clinical presentation and disease course, ARF and PSRA are separate disease entities. Development of validated diagnostic criteria for PSRA is mandatory to proceed with studies on pathophysiological mechanisms and treatment in PSRA.