In Poland the poultry industry is dynamically developing and, as a result, constant threat from the rapidly changing IB virus explains the need to constantly monitor the epidemiological situation in a given region. Therefore, the aim of this publication is to present the current epidemiological IB field situation in Poland based on research done recently. Knowledge of the current field status can help to find the best solution and quick response in the case of a new variant of IB virus with altered pathogenicity. The following publication shows changes in the epidemiological situation in the frequency of infections with various IB virus serotypes, mainly 793B, Var2, and QX. Understanding the epidemiology of IBV and the structure of the occurrence of individual viral serotypes allows the use of optimal vaccination programmes and improvement of production efficiency.