Most of the previous studies have shown a significant inverse relationship between smoking during pregnancy and weight, height and head circumference of infants at birth, but there is limited literature that assesses the head circumference measures of infants of smoker mothers in postnatal follow-up. The aim of this study was to assess the effects of maternal smoking and passive smoking during pregnancy on postnatal anthropometric measures of infants. Infants were divided into 3 groups: infants of smokers (n = 48), passive smokers (n = 57) and nonsmokers (n = 54), and were evaluated for their weight, height and head circumference at birth, 3 months and 6 months of age. Infants of smokers showed significant weight and head circumference deficits at birth compared to nonsmokers' infants (p < 0.05 and p < 0.001, respectively). At 6 months of age, infants of smokers continued to show significant deficits in all 3 measures compared to nonsmokers' infants (p < 0.001 for each), and infants of passive smokers showed only marginal decreases. Moreover, the weight and height growth velocities of the smokers' infants remained deficient, whereas their growth velocity of the head circumferences increased from birth up to 6 months and reached the growth velocity of the nonsmokers' infants. Infants of passive smokers showed a complete catch-up growth at 6 months. This study indicates that smoking during pregnancy results in serious deficits in infants' growth even after birth. Therefore, it is essential to inform smoker women before pregnancy the possible growth retardation of infants.