Objective To explore the effect of low birth weight of children on their intelligence and their behavior. Methods Twenty children born with full term and low birth weight, 20 born with preterm and low birth weight, and 20 born with full term and normal birth weight were evaluated by intelligence and child behavior at six years of age. Results The average intelligence of all the 3 groups are in normal range, and the difference are not statistically significant, but the difference of child behavior check are statistically significant( P