To determine whether there is any difference in the growth of the cerebellar vermis between appropriate-for-gestational-age (AGA) and small-for-gestational-age (SGA) infants during fetal life, the central vermian area (Cva) of the cerebellum and its anterior-posterior distance (Vap) and superior-inferior distance (Vsi) were measured by midsagittal cerebral ultrasonography in 218 newborns within 24 h of birth. Patients with congenital infections and malformations were excluded. One-hundred twenty-one infants were AGA and 97 SGA. Best curve-fit of second-degree polynominal equations were found between gestational age and Cva, Vap, Vsi in both AGA and SGA neonates. Among them, Cva correlated best with gestational age in both AGA and SGA newborns. Comparing the head circumference (HC), Cva, Vap and Vsi between AGA and SGA neonates in the four gestational age subgroups (24-28, 29-33, 34-37 and 38-41 weeks), significant differences in HC were found in the 34-37 weeks (P < 0.01) and 38-41 weeks (P < 0.001) subgroups. But the significant differences in Cva and Vsi were found only in the 38-41 weeks subgroup. There is more accelerated growth in vermis from 34 to 41 weeks of gestation than that from 24 to 33 weeks. Comparing with AGA, the non-fetal cause of intrauterine growth retarded newborns demonstrate growth retardation in the cerebellar vermis only at late gestation. The cerebellar vermis measured by cranial ultrasound may serve as part of the neurological maturation assessments in newborns. Further work is needed to establish the normogram for the cerebellar vermis in newborns, and to assess the neurodevelopmental outcomes of those with an abnormal vermis.