OBJECTIVE: To study the insular development of small for gestational age (SGA) infants. METHODS: The insular area and circle were measured by cerebral ultrasonography in 92 SGA infants. The results were compared with those from 109 appropriate for gestational age (AGA) infants. RESULTS: The insular area and circle were positively correlated with the birth weight and gestational age in SGA infants. The insular area in SGA infants with a gestational age of either >37 weeks (451±92 mm2 vs 516±116 mm2; P37 weeks was also significantly less than that in the AGA infants (92±11 mm vs 97±11 mm; P<0.05). CONCLUSIONS: The insular development of SGA infants seems to be immature. The insular development may be assessed based on the insular area and circle measured by cerebral ultrasonography.［Chin J Contemp Pediatr, 2009, 11 (9):733-735］