In a catchment area with population of approximately 60,000 in Libya for a period of two years and three months a group of 38 children aged 7-12 years with the diagnosis of rheumatic fever was followed up. An incidence of cca 60 attacks of rheumatic fever per 100,000 children per year was recorded. The clinical picture of primary attacks did not differ from the clinical picture of primary attacks in technically advanced countries in the sixties and also the development of the finding on the heart in rheumatic patients with penicillin prophylaxis was equally favourable.