The study deals with the investigation results of psychodynamic factors relevant to the explanation of criminal behaviour. The research has been carried out on a sample of ten subjects sent to forensic psychiatric examination through court order, in order to evaluate their accountability and to suggest possible treatment. The sample included the diagnostic category of personality disorders only. Persons with psychotic disturbances, alcohol and drug addicts, mentally retarded and delinquents with organic-cerebral damage were not taken into consideration. The method of studying individual cases by means of psychodynamically oriented analysis of the subjects' development and other available data have been applied. The obtained results suggest that socialization defects, located in pregenital development phase are basis for criminal behaviour. The defects are due to badly disturbed object relations mainly in the oral and anal phase of development. In the subjects, narcissistic personality disorders can be diagnosed, while neurotic symptoms are present in a smaller degree. Criminal behaviour of these people can best be understood in the context of the theoretical concept of early narcissistic configurations actualization: grandiose self and idealized image of parental figures. In such cases the release of aggressiveness has been provoked, as a rule, by immediate endangerment of the self and by uncertain sexual identity. Unconscious feeling of guilt and need for selfpunishment appears often as criminal action driving forces. In all the subjects, structural disturbances in ego and superego formation were diagnosed. Greater integration of psychoanalytic knowledge into the theory and praxis of forensic psychiatry imposes itself as an indispensable basis for the reforms which are already under way and which are excepted in the future development of forensic psychiatry.