The fatty acid composition of plasma cholesterol esters, plasma phospholipids, erythrocyte phosphatidylcholine and erythrocyte phosphatidylethanolamine was investigated in severely malnourished Nigerian children with kwashiorkor (n = 12) and marasmus (n = 32). Normally nourished children from the same area (n = 23) served as controls. The malnourished children showed a significant reduction of highly polyunsaturated fatty acids in cholesterol esters, phospholipids and phosphatidylcholine. No differences between the groups were found in erythrocyte phosphatidylethanolamine. Children with kwashiorkor had lower levels of linoleic acid metabolites and docosahexaenoic acid than marasmic children. The results suggest that the kwashiorkor syndrome is associated with impaired desaturation and elongation of PUFA and/or increased lipid peroxidation.