Low birth weight is a key determinant in the risk of morbidity and mortality in the neonatal period and during childhood. This unmatched case-control study in Hamadan, Islamic Republic of Iran, compared the characteristics of mothers of low-and normal-birth-weight infants. Maternal sociodemographic data, pregnancy history, anthropometric data and cord plasma zinc level were collected from 134 mothers of low-birth-weight infants and 134 mothers of normal infants at the time of delivery. Significant differences in maternal characteristics namely gravida, parity, body mass index, maternal weight gain during pregnancy and plasma cord blood zinc were found between low-and normal-birth-weight infants. There were no significant differences in maternal age, maternal education, maternal occupation, family income, previous abortion, previous preterm labour, birth interval, type of clinic and place of residence between the 2 groups.