Human granulocytic anaplasmosis (HGA) and Lyme borreliosis (LB) are tick-borne and emerging infectious diseases caused by the Anaplasma phagocytophilum and Borrelia burgdorferi species. In Europe, including Slovakia, the principal vector of both pathogens is the common tick - Ixodes ricinus, in which double infections with these pathogens have been reported. The aim of our study was evidence of IgG antibodies against A. phagocytophilum in blood sera of humans with suspects LB from several Clinics of University Hospitals, and the evaluation of the possibility of B. burgdorferi and A. phagocytophilum co-infection in examined patients. The serological method ELISA was used to detect IgM and IgG antibodies against B. burgdorferi. Anti-A. phagocytophilum IgG antibodies were analyzed by the A. phagocytophilum Indirect Immunofluorescence Antibody (IFA) IgG test. A total of 214 human samples (91 men, 123 women) were obtained from patients living in Kosice town and in villages around Kosice (Eastern Slovakia). IgG antibodies against A. phagocytophilum were detected in 15 cases (6 men, 9 women), which represented 7.0 % positivity. Two cases of the co-infection B. burgdorferi with A. phagocytophilum, which equals 0.93 % of the total number, were found.