This paper reviews 75 infants with myelomeningocele treated either at birth or from an early age at Rainbow Babies and Children's Hospital, for whom complete records and psychometric testing (IQ) are available (including complete summaries from referring hospitals). Three groups are compared: (1) infants without complications who were shunted for hydrocephalus (n = 41); (2) infants with complications who were shunted (n = 16), and (3) infants who were not shunted (n = 18). Complications were defined as ventriculitis (positive CSF cultures with elevated protein, depressed glucose and inflammatory cells), anoxia, poorly controlled hydrocephalus or other CNS anomalies such as porencephaly. The mean IQ of infants who were not shunted was 104, of those shunted without complications it was 91, and of those shunted who had complications it was 70. These IQ differences were significant at p less than 0.01, and were not explained by differences in spinal lesion levels.