Selected tests from the Halstead-Reitan neuropsychological battery were administered to 10 male individuals who had been diagnosed as autistic in early childhood. Results from the battery obtained from the autistic group were compared with a group of retarded persons matched for IQ and with a group of patients with demonstrable diffuse brain damage. As a group, the autistic subjects showed a pattern of deficits indicative of a significantly greater degree of left hemisphere dysfunction than either comparison group. Furthermore, within-subject comparisons revealed that the autistic group had a significantly greater left than right hemisphere dysfunction, while neither comparison group showed this lateralized pattern.