The paper summarises the long-term studies on factors and mechanisms of psychosomatic disorders at the Department of Clinical Psychology of the Pacific State Medical University. The aggregate sampling comprised 3738 children and teenagers suffering from different forms of psychosomatic disorders, 383 healthy children and teenagers, and 1490 pregnant women and mothers. It allowed detecting relevant factors contributed to the development of psychosomatic disorders like high levels of psychology-related prenatal risk factors, labour induction with caesarean section and birth asphyxia during vaginal delivery, specific maternal-infant relations characterised by an increased attention to symptomatic physical manifestations, and inadequate types of family education. The mechanisms of psychosomatic disorders include disorders related to the development of self-consciousness from somatognosis, spatial representations, strategies for optical spatial activity down to inadequately low self-appraisal, and therefore, prevalence of deficient and destructive I-functions in a teenager’s personality structure.