The aim of this paper is to compare susceptibility to the Stroop effect in men with schizophrenia and in men with frontal lobe lesions. A sample of 90 men participated in the study. They were divided into three groups: men with schizophrenia (n = 30), men with localized frontal lobe lesions (n = 30) and healthy men (n = 30) as a control group. Significant differences measures found between controls and men with schizophrenia in all of the analyzed variable (Control task execution time p < 0,001; Interference task execution time: p < 0,001; Difference between two times p < 0,05). Men with frontal lobe lesions differed significantly from healthy controls in the terms of speed of the task execution (Control task execution time p < 0,01; Interference task execution time: p < 0,01), but were no more prone to the Stroop effect than healthy controls. No significant differences were found between schizophrenia and frontal lobe lesion groups.