The purpose of the study was to assess the extent and nature of malnutrition in young children in Jamaica in a manner useful for governmentplanning. 489 infants and young children under 4 years of age were examined in three urban and nine rural localities previously studied in 1963-4. The peak period of weight failure was in childrenaged 9-24 months, a quarter of whom were below 80 percent of standard weight. No difference in average weights for age between 1963-4 and 1970 were detected. The peak period for height failure was between 12 and 18 months. 57 percent of the secotrants had a chest/head circumference ratio less than 1.0 and 37 percent in their fourth year were still abnormal in this respect. More children had abnormally thin triceps skinfolds than had small armmuscle circumferences. The results are discussed in relation to each other and to other surveys, to mortality rates, to the foodbalance sheet of Jamaica and to a food consumptionsurvey carried out in 1963-4. The conclusions are drawn that inadequate breast-feeding occurring against a background of poverty and often inadequate and inappropriate supplementation has resulted in an early onset of protein calorie malnutrition - predominantly a deficiency of total calories rather than of protein. Malnutrition is more prevalent in rural than urban areas. No change in overall nutritional status of infants and young children in Jamaica between 1963 and 1970 could be detected (AU)