Ixodes tick-borne borrelioses (ITBB) are caused by two different spirochetes: Borrelia from the group of Borrelia burgdorferi sensu lato, the agents of the classic Lyme borreliosis (LB), and Borrelia miyamotoi that belongs to the group of Borrelia causing tick-borne relapsing fevers. ITBB caused by B. miyamotoi (BM-ITBB) is a previously unknown infectious disease discovered in Russia. It is known that the LB sequelae may reduce the long-term life guality of convalescents. Aim. To study the follow-up of those who have recovered from new BM-ITBB infection in comparison with persons who have had LB. Subjects and methods. The investigation enrolled 41 patients with BM-ITBB and 41 patients with LB who were treated at the Republican Infectious Diseases Hospital of Udmurtia. Within a year after the disease, they were followed up through clinical and instrumental examination of cardiac performance, expanded biochemical analysis of blood and urine, which could; estimate kidney and liver functions, and psychological questioning. Results. Asthenic syndrome and complaints about and objective signs of cardiac dysfunctions persisted supraventricular extrasystoles, left ventricular diastolic dysfunction, and elevated and/or unstable systolic blood pressure were detected in 20-30% of the convalescents for a long time. Kidney dysfunctions were manifested in albuminuria and the decrease of glomerular filtration rate. A year following the disease, 10-20% patients had persistently elevated concentrations of alanine aminotransferase, aspartate aminotransferase, and C-reactive protein and had higher levels of total cholesterol and low-density lipoproteins. The pathological consequences of ITBB were polymorphic and varied in different patients; in general, only 68% of them showed health improvement. Conclusion. We assume that a significant role in the pathogenesis of BM-ITBB and LB is played by vascular endothelial damage possibly associated with the inflammatory and autoimmune aspects of an immune response in Borrelia infection. The consequences of this damage may persist and even intensify during a year, which provokes chronic dysfunction of the heart, kidney, or liver in a number of convalescents.