Blood serum samples collected from randomly selected groups of 32 pigs and 41 cows reared in farms belonging to the rural community “A” located in eastern Poland and exposed to the Vistula river floods, and serum samples from groups of 41 pigs and 40 cows from farms belonging to the rural community “B” located also in eastern Poland but not in the area exposed to floods, were examined by the microscopic agglutination test for the presence of antibodies against 18 Leptospira serovars. The percentage of serum samples presenting positive results with at least one serovar were higher in pigs and cows from community “A” comparing to community “B” (34.4% vs. 4.9% and 26.8% vs. 15.0%, respectively). In the case of pigs, the difference was statistically significant (P=0.0015). The reactions with 12 Leptospira serovars (Australis, Bataviae, Bratislava, Canicola, Hardjo, Hebdomadis, Icterohaemorrhagiae, Pomona, Poi, Cynopteri, Grippotyphosa, Celledoni,), belonging to four species (L. interrogans, L. borgpetersenii, L. kirschneri, L. weili) were found in the examined animals. In community “B”, six reactions with one serovar and two reactions with two serovars were noted whereas in community “A” - 19 reactions with one serovar, one reaction with two serovars and two reactions with six serovars were observed. The titres in animals reared in community “A” were significantly higher (up to 25,600) compared to community “B” (up to 200, P=0.0094). The obtained results suggest that the exposure to flooding may increase the infection rate in pigs and cows from afflicted areas to some extent.