This experiment was carried out to establish the immunohistochemical diagnostic method for infectious pancreatic necrosis in the monolayers of CHSE-214 cell cultures and paraffin-embedded tissue sections from rainbow trout infected with infectious pancreatic necrosis virus(IPNV). Specific identification of IPNV antigens was often demonstrated in the pancreatic exocrine cells, and less in the intestinal mucous epithelia and the renal hemopoietic tissues by the use of monoclonal antibodies against capsid protein VP2. The specific reaction was seen as a distinct red cytoplasmic color, often as small granules of various sizes. The result showed that streptavidin alkaline phosphatase immunohistochemisry specifically identified IPNV antigens in both infected cell cultures and tissue sections