A system for classifying protein energy malnutrition in children based on percentage of expected weight for age and the presence or absence of oedema. Between 60 and 80% of expected weight is underweight in the absence of oedema, and kwashiorkor if oedema is present; under 60% of expected weight is marasmus in the absence of oedema, and marasmic kwashiorkor if oedema is present.