Infection is a common occurrence in children with kwashiorkor. It has been suggested that infection in kwashiorkor results from immune depression, and that the immune depression of kwashiorkor is caused by a diet-associated elevation of prostaglandin E2 (PGE2). The purpose of this study was to determine whether levels of PGE2 are abnormal in children with kwashiorkor.Plasma PGE2 and plasma proteins were measured in children admitted with oedematous kwashiorkor, and compared with PGE2 in children with cerebral palsy.Plasma PGE2 was higher in children with kwashiorkor than in control children (7.25 +/- 3.5 v. 3.51 +/- 1.59, P < 0.01). Within the kwashiorkor study group there was a significant negative correlation between log-transformed serum PGE2 and total plasma protein (r = -0.59, P < 0.001), plasma albumin (r = -0.63, P < 0.001), weight-for-age (r = -0.37, P < 0.05), and height-for-age (r = -0.37, P < 0.05). The difference in mean values of PGE2 in children with kwashiorkor who recovered from the illness and those who died was not significant (7.1 +/- 2.6 v. 9.1 +/- 4.8, P = 0.36).Significantly higher PGE2 levels in children with kwashiorkor provide adequate reason for the depression of immune function known to occur in these children. Elevated PGE2 levels may also be implicated in other components of the illness.