Aim. To study blood coagulation and microcirculatory disorders as a possible cause of transient dysfunctions of organs (the kidney, liver, heart, lung, etc.) in patients with ixodid tick-borne borreliosis caused by Borrelia miyamotoi (Bmt). Subjects and methods. Twenty-four patients with Lyme disease (LD) and 28 Bmt patients treated at Izhevsk City Hospital (Udmurtia) were examined in the study. Platelet counts and the presence of D-dimers were determined; activated partial thromboplastin time, prothrombin time, thrombin time, fibrinogen and antithrombin III levels, and Factor XIIa-dependent fibrin clot lysis time were measured. Slit lamp microscopy of the conjunctiva was also carried out.  Results. Platelet counts were less than 150,000 per μL of blood in 43% of the Bmt patients. All the Bmt patients had at least one abnormal coagulation parameter of the eight ones that were tested; 64% of them had marked coagulation disorders with three or more abnormal laboratory findings. In contrast, all the eight parameters were normal in 71% of the LD patients. The other seven LD patients had only one or two abnormal coagulation parameters (p<0.001 in comparison with Bmt patients). Microscopic examination of eye capillary blood flow revealed pathological findings that included aggregates of erythrocytes and obstructed and/or sinuous capillaries in 22 (79%) of the Bmt patients, but none of the LD patients. A total of 14 Bmt patients had both coagulation and microcirculatory abnormalities. Eleven of them also had transient signs of organ dysfunction. Conclusion. As far as Borrelia secrete no known toxins, we hypothesized that uncovered disorders of blood coagulation and microcirculation in Bmt patients may contribute to organ dysfunction.