In the Kingston Project malnourished children referred from public health clinics to a metabolic ward were treated at home using community health aides within the existing health service. We have previously provided anthropometric results showing significantly greater gains in weight and length for groups given a high energy supplement (3.31 MJ daily) for 3 months during treatment, and greatest gains for a group treated with metronidazole at the beginning of supplementation [Heikens et al., Eur. J. Clin. Nutr. 43, 145-160 (1989); 47, 160-173 (1993)]. We now present findings on morbidity and relate these to the separate interventions and to growth velocities. Although referral was solely on nutritional criteria, 65% of the sample were found to have additional illnesses at enrollment. During the study period (6 months) upper respiratory tract infections (URTI) were the commonest illness in all groups; there were significantly more gastroenteric infections in the group given the supplement, but not the antibiotic, treatment; the children who received only the standard health service care were ill more often and for longer periods than children in the other groups. Diarrhoea, fever and dysentery prevalences were all found to relate significantly to weight velocity, and although prevalences differed between treatment groups, the detrimental effect on velocity was similar whichever the group.