The authors have used body mass index (BMI: kg/m2) to assess the Vietnamese adult nutritional status and classified the population into different grades of chronic energy deficiency (CED). CED is prevalent in Vietnamese adults (average 40%). The mean value of BMI of the age group 26-40 years is 19.7 but it decreases thereafter except in urban areas. The BMI curve of distribution is different between adults living in rural, urban and mountainous areas. There seems to be a relation between BMI of mothers and the nutritional status of their < 5-year-old children. The survey also revealed a relation between maternal BMI and birth weight, and between CED and the health status of the population.