AbstractObjectiveTo assess the neurodevelopmental outcome of children with prenatally diagnosed isolated microcephaly defined as head circumference more than 2 SD below the gestational mean.MethodsChildren aged 2–6 years who had been diagnosed in utero as having head circumference measurements more than 2 SD below the gestational mean were compared with normocephalic children, utilizing a standard neuropsychological battery. Comparisons were also made within the study group.ResultsHCs were between −2 and −4.8 SD, only one fetus having a HC below −3 SD. Children with a prenatal head circumference between 2 SD and 3 SD below the gestational mean did not differ significantly from the control group regarding cognitive, language and motor functioning. However, they exhibited more behavioral‐emotional problems. There were no significant differences between children who had suffered from intrauterine growth restriction and those who had not, or between those with familial and those with non‐familial microcephaly. Nevertheless, linear regression analysis showed that head circumference in utero helps predict cognitive functioning later in life.ConclusionsPrenatally diagnosed head circumference between 2 SD and 3 SD below the gestational mean is not a risk factor for later abnormal neuropsychological development. Copyright © 2010 ISUOG. Published by John Wiley & Sons, Ltd.