Tick-borne encephalitis (TBE) is vectore borne viral disease caused by arbovirus belonging to genus Flavivirus, family Flaviviridae. In the last ten years, this zoonosis increased its geographical distribution, as well as pathogenicity, while in some areas occures as reemergent disease and its significance is thus greatly increasing. TBE is considered endemic in northern Croatia, so the aim of this diploma thesis was to for the first time in Croatia determine seroprevalence of TBE in domestic animals, particularly dogs and to compare it with other similar studies in Europe. Samples used in this thesis were collected from the archives of the Central laboratory of Department of Internal Medicine, University of Veterinary Medicine, Zagreb. The study included 178 dogs: 45 mongrel dogs and 133 pure bred dogs. The average age of dogs was 7 years. Dogs were devided in to two groups regarding their purpose: group of hunting and non hunting dogs. In the group of non hunting there was total of 167 serum samples. We searched 82 serum samples of males and 85 of females. Regarding the evidence of previous infection with Babesia spp. 40 of searched samples were of infected and 127 samples of uninfected animals. Furthermore, in the group of hunting dogs there were 11 serum samples. We searched 7 serum samples of males and 4 of females. Regarding the evidence of previous infections with Babesia spp. 7 of searched dogs were infected and 4 dogs were uninfected. Samples were examined with ELISA method with a commercial diagnostic kit "Immunozym TBE IgG All species" (Progen Biotechnik, Heidelberg, Germany). The results showed that 1.12% of samples were seropositive to TBE. Two serum concentrations of IgG - KE were positive (127 VIEU/ ml and 428 VIEU/ml). Results of this study confirm the need for further similar studies in other areas of RH, as well on the other animal species so we could more accurately determine seroprevalence of TBE in RH. Because of proven seroconversion, dogs could also be used as sentinel animals for monitoring the risk of infection with TBE, which is also very important from a public health point of view.