Conducting serological analyses for Mycobacterium avium subsp. paratuberculosis (MAP) infections is one of the initial step towards evaluating the existing epizootic threat. The reported study was undertaken in order to investigate the seroprevalence of MAP in the area of Zuławy Wiślane, characterized by land conditions favourable for the survival of this mycobacterium in the environment.The experimental material was collected from 3961 animals over two years of age bred in 187 herds of dairy cattle. Serological analyses demonstrated 138 MAP-positive animals in 38 herds. The analysis of the occurrence of seropositive animals showed that the highest seroprevalence occurred in large herds (herd size > 100 cows) and in groups of imported animals.