Unlike many brain injured children who are often rather difficult, toddlers and school-aged children with congenital vein of Galen malformations (n = 20; age range, 4 months to 12 years with a mean of 4 years) evidence a relatively positive temperament profile (based on the Temperament Scales of Carey, McDevitt, Fullard, Hegvik, Medoff-Cooper). They do not, however, differ from normal children with regard to the frequency of easy, difficult, slow to warm up, and intermediate temperament clusters. The temperament profile of children with vein of Galen malformations appears unaffected by additional neurologic abnormalities (hydrocephalus, abnormal developmental quotient, seizure disorder, focal cortical lesions) or other factors including age at testing, sex, or socioeconomic status. Contrary to the findings in adults of right hemisphere dominance for attention, presence of additional right-sided focal cortical pathology was not associated with greater activity level, distractibility, or impersistence. In contrast to the findings in adults and children of right hemisphere dominance for emotions in general, children with vein of Galen malformations and additional right hemisphere cortical damage are not more difficult than those with additional left cortical pathology or no additional focal cortical pathology. The fact that the pathology in vein of Galen malformations is subcortical may explain their relatively easier temperament and the absence of lateralization effects.