Acute rheumatic fever in West Virginia. Not just a disease of children. Rheumatic fever is a poststreptococcal disease that is receiving renewed attention by the medical community. We describe a recent increase in the number of observed cases of acute rheumatic fever (ARF) in West Virginia. This is the fifth report of a recent increase in the incidence of ARF in the Ohio Valley area in the last 4 years. In contrast to the other reports, nearly two thirds of our cases of ARF were in adults, more than half of whom had suffered previous bouts of ARF. In these adults with recurrences, none was taking prophylactic penicillin at the time of presentation. Carditis was present in seven adults, two without a history of carditis. Arthritis was present in all adult patients. These data indicate a possible geographic phenomenon related to the increased number of observed cases of ARF and document that ARF is not simply a disease of childhood. Furthermore, our findings highlight the need for extended penicillin prophylaxis for secondary prevention of ARF, especially for those with an increased risk of acquiring a streptococcal upper respiratory tract infection. 