In order to investigate the relationship between age at injury and long-term neuropsychological impairment, 29 children and adolescents who sustained traumatic brain injury (TBI) were studied at least 6 years post-trauma. Tests of intellectual, memory, visuospatial and frontal lobe functions were administered to patients and 29 normal matched control subjects. Correlations between performance on neuropsychological tests and age showed the following direction: the younger the child when TBI was sustained, the worse the cognitive outcome. After controlling for injury severity, visuospatial functions remained related to age. Patients' performance differed significantly from that of controls in half of the neuropsychological variables analysed. To further investigate the effects of age at injury, the sample was divided in two groups (TBI before and after age of 8) and then compared with their respective controls. Patients damaged earlier presented impaired intellectual and visuospatial functions. The results suggest that neuropsychological sequelae remain after at least 6 years of evolution, and that there is an age at injury effect.