Today the nature of neuropsychological syndromes in various corpus callosum (CC) pathology remains an open question. We have examined 30 subjects with cc pathology. All subjects performed the procedure of fixed set by D.N. Uznadze. The analysis of the results demonstrated connection between fixed set functioning and condition of left hemisphere and access to it. The most prominent impairment of set forming dynamics was demonstrated by the subjects with CC pathology. However these subjects have also demonstrated posterior right hemisphere deficit in standard neuropsychological examination. Thus, we can conclude the dissociative nature of the interhemispheric impairment syndrome.