Antisaccade task performance and mean amplitudes of slow cortical potentials (contingent negative variation—CNV) were investigated in 19 healthy volunteers, 16 schizophrenic patients (SP), and 12 patients with stereotyped form of paraphilia (PP). Compared with healthy subjects, schizophrenic and paraphilic patients committed significantly more erroneous saccades. The clear between-group CNV differences were observed during the early CNV stage that is associated with cognitive aspects of preparatory set. In SP, as compared to controls, the significant decline of CNV amplitude was found at frontal-central area. PP have demonstrated the lack of CNV over central and parietal regions, but their CNV amplitudes in frontal area did not differ from values of control group. Thus, two distinct types of CNV abnormalities have been found. The SP results have been interpreted as support for frontal dysfunction in schizophrenia. The disconnection between prefrontal cortex, sensorimotor cortex, and related subcortical structures is hypothesized in paraphilia group.