Mental disorders were studied in 52 patients with acquired complete heart block (CHB) before and after pacemaker implantation. Mental state of the patients was characterized primarily by borderline mental pathology - asthenia, affective pathology, hysteria spectrum disorders with autonomic symptoms and hypochondriac disorders. The structure and expression of mental disorders depend on premorbid personality traits of the patients, duration, severity and stage of the disease, the phase in respect to surgery intervention as well as preoperative period duration. Being the main therapy method, the operative CHB treatment, in general, positively influences the dynamics of mental disorders. However, in some cases, pacemaker implantation changes the behavior and quality of life of patients. Peculiarities of mental disorders in the CHB demand to include of psychopharmacotherapy and psychotherapy in treatment process.