Geographically different strains of Borrelia burgdorferi sensu lato (B. burgdorferi sensu stricto Ir 105, B. burgdorferi s.s. + B. afzelii V 123, B. garinii Ir 112 - isolates from eastern Slovakia, B. garinii K24 - isolate from western Slovakia and B. burgdorferi s.s. B 31 - American strain) were compared as antigens for serological study of Lyme borreliosis by IgG ELISA on a group of horses from eastern Slovakia. In a set of 101 horse serum samples, positivity with the use of Ir 105 strain was 53 (52.4%), with V 123 51 (51.49%), with Ir 112 48 (47.5%), with K 24 47 (46.5%) and with B 31 only 25 (24.7%). The seroprevalence between strains B 31 and Ir 105, B 31 and V 123, B 31 and Ir 112, B 31 and K 24 differed statistically significantly (test chi2, p<0.05); however, the differences between strains Ir 105, V 123, Ir 112 and K24 were insignificant. Consistency of positive and negative findings between American and Slovak strains ranged from 50.5-62.4%. Comparison of Slovak strains (Ir105, V 123, Ir 112 and K 24) consistency of positive and negative findings was higher from 79.2-95.04%. The highest consistency of findings was reached comparing strains Ir 112 and K 24, and the same high agreement of results was observed between the strains Ir 105 and V 123 and also Ir 112 and Ir 105. Higher consistency of findings of serologically examined horses with geographically close trains is in accordance with greater similarity of protein profiles of Slovak strains compared to the American strain.