Schizophrenic patients are characterized by failure of social interaction, which leads to deterioration of their well-being. One of its manifestations is reduction of Machiavellianism. There is a hypothesis, that it is generated by cognitive deficit of the patients – general or affecting only social cognitions. On the other hand, it may be the consequence of diminished motivation and asociality of the patients. The objective of the present work is to check cognitive and motivational hypotheses of diminished Machiavellianism in schizophrenia with the help of psychological and genetic approaches. The sample consisted of 274 schizophrenic patients. The control group consisted of 234 normals. To evaluate Machiavellianism we used the scale Mach-IV, for cognitive sphere – tasks on verbal memory, executive functions, facial emotion recognition and theory of mind, for affective-motivational sphere – psychometric instruments EPI, STAI and PANSSS. The subsets of patients were genotyped for polymorphisms in the HTR2С, COMT, DRD2 genes, as well as serotonin transporter (the subsets sizes were 186, 153, 134 and 204 patients correspondingly). The values of Mach-IV scale in patients were lower than in controls. In schizophrenia the more significant Machiavellianism reduction coincided with higher composite scores of basic cognitions, increase in passive-apathetic social withdrawal, decrease in anxiety and emotional withdrawal. We didn’t find any gene effects and their interaction that would shed light on the mechanisms of diminished Machiavellianism in patients. The data gives evidence against cognitive hypothesis, shows moderate input of motivational failure of socialization in Machiavellianism reduction and allows assuming that low Machiavellianism of patients is not the “drop-out” of the function, but the result of work of defensive mechanisms of personality.