The study was conducted in June/2008 in Nui Doi town - Kien Thuy district  – Hai Phong. Objectives: to determine malnutrition rate and describe some risk factors related to malnutrition in children. Subjects: 313 children under 5 and 313 mothers were enrolled in the study. Child malnutrition was classified by WHO method using NCHS reference and comparing with WHO – standard growth. Method: Cross-sectional study. Results: Low weight was 12.46%, stunting 12.78%, wasting 3.51%. When comparing malnutrition rate based on NCHS and WHO reference, underweight 2.88% was higher stunting 1.28% and wasting  was 2.88% lower. - Breastfeeding duration after birth, weight at birth, starting time for giving solid food to the child , time for weaning, maternal age, number of children in the family, communication for mothers were determined to be related to malnutrition in children.