A case of a male patient with chronic Lyme borreliosis running with marked neurological symptoms (Garin-Bujardoux-Bannwarth syndrome) is reported. Two years before the disease manifestation the patient was infected by the tick with both borrelia and Rickettsia sibirica. The latter infection provoked an acute fever in tick-borne rickettsiosis immediately after the tick's bite. This masked development of Lyme borreliosis which manifested only 5 months later as a neurological disease. It is thought necessary to propose a rational scheme of antibiotic treatment of patients with tick-transmissible diseases.