The medical history, clinical features and investigations of 145 children with kwashiorkor were compared with 113 marasmic kwashiorkor, 158 marasmic children and 186 nutritionally normal controls of similar age admitted to hospital in Khartoum. Factors in the group with protein-energy malnutrition (PEM) which could relate to aetiology include: a history of prolonged illness and anorexia, frequent and prolonged episodes of diarrhoea and recent measles. The delay in achievement of developmental milestones in PEM children probably reflects the frequent and chronic illnesses in this group. An episode of previous oedema was reported in 22 per cent of marasmic kwashiorkor, 12 per cent of kwashiorkor and 12 per cent of marasmic children. Though hair and mucosal changes and enlarged liver were more common in the marasmic kwashiorkor and kwashiorkor groups, they were also common in marasmic children. There was no significant difference in behaviour (apathy, irritability, anorexia) between kwashiorkor and marasmic children. The classical skin changes of kwashiorkor were only seen in the oedematous children. The mortality was 19 per cent in kwashiorkor, 35 per cent in marasmic kwashiorkor, and 14.5 per cent in the marasmic group. The major differences between marasmus and kwashiorkor children were that the kwashiorkor children were reported larger at birth, achieved more normal developmental milestones, were taller and had larger head circumference than the marasmic children. The implications of these findings in relation to aetiology are discussed.