Dimensional complexity reflects the number of independent variables contributing to a dynamic process. EEG epochs recorded from 12 neuroleptic-free schizophrenic patients and 11 normal control subjects were Laplacian-filtered to highlight activity specific to prefrontal and parietal areas, and dimensional complexity measures of the resulting signals were then derived. Complexity of EEG waveforms generated by schizophrenic patients was depressed relative to that of normal subjects, especially in left frontal and right parietal regions. These data suggest that complexity of underlying is also reduced.