We undertook a retrospective analysis of the incidence of acute rheumatic fever (ARF) in Memphis-Shelby County during the five-year period from 1977 through 1981. Cases were identified by review of local hospital records and by mail and telephone communication with 327 primary care physicians and neurologists. Forty-one patients met the modified Jones criteria, of whom 16 had conditions that were diagnosed in Memphis but who resided elsewhere. The overall ARF incidence among Memphis-Shelby County residents was 0.64 cases per 100,000 population each year. The highest rate, 3.74, was found among blacks aged 5 to 17 years residing in the inner city, while white children in the suburban and rural areas had a rate of only 0.49. Current strategies for prevention and diagnosis of ARF must take into account the extraordinarily low level to which the incidence of the disease has fallen in certain suburban US populations.