Abstract The aim of this study is to compare the results from the histopathology and the immunohistochemical method in the diagnostic of Porcine circovirus type 2 (PCV2) infection in pigs. The circovirus infection is a pig disease that is caused by a small, spherical, nonenveloped virus with a single stranded DNA genome which is spread throughout the pig industry worldwide. The circovirus is the etiological agent of a several pig diseases which today are thought to be the cause of the greatest economical loses in pig production. The most important of these diseases is the PMWS (post-weaning multisystemic wasting syndrome). In this article we have performed an investigation of four farms on which there had been a previous clinical diagnosis of the Post-weaning multisystemic wasting syndrome. The examination was performed on thirty pigs from these farms, from two to five months old, which had the most severe symptoms of the disease. Necropsy, histopathology and immunohistochemical diagnostic methods were performed. The most significant necropsy findings were the enlarged lymph nodes (especially the inguinal, mediasinal and the mesenteric lymph nodes). The main histopathological changes were located in the lymphatic organs presented by B and T lymphocyte depletion and increase in the number of the macrophages. PCV2 antigen and nucleic acid were detected in almost all of the examined tissues. The examination showed that the histopathological and immunohistochemical methods provide complementary results in diagnosing PCV2 in pigs.