The aetiology and pathogenesis of kwashiorkor remains obscure. Clinical and epidemiological studies are in progress in Sudan to determine whether aflatoxins play a role in the pathogenesis of kwashiorkor. Local foods are screened for their aflatoxin content and children with kwashiorkor and age and sex matched children with marasmus and with normal nutrition are being investigated for aflatoxins in their blood and urine. Autopsy liver samples of children with kwashiorkor and other nutritional disorders in Nigeria and South Africa have been examined for their aflatoxin content. Aflatoxins are detected using two dimensional thin layer chromatography and high performance liquid chromatography. Results to date on over 350 children studied show that aflatoxins occur more frequently and at higher concentrations in the sera of children with kwashiorkor than in children with marasmus or in normal children. Urinary excretion of aflatoxins in kwashiorkor appears to be less than in other groups. In the autopsy liver samples, aflatoxins have been detected in all kwashiorkor livers but not in livers from marasmic children. These findings seem to implicate aflatoxins in the pathogenesis of kwashiorkor. If this is confirmed it would have very wide implications for the management and prevention of kwashiorkor.