In this study, it was aimed to evaluate the levels of interleukins such as IL-1β, IL-6, IL-10 and IL-12β in sheep with Jaagsiekte by immunohistochemical methods. In this way, it will be revealed whether interleukins are effective in the progression of Jaagsiekte and how useful they are in the diagnosis of the disease. The material of the current study consisted of lung tissues of 26 sheep (Control, n=6 and Jaagsiekte, n=20) brought to the Department of Pathology for routine histopathological diagnosis. Tissue samples taken were fixed in 10% buffered formaldehyde solution. 5 µm-thick sections were taken from the paraffin blocks prepared after routine tissue follow-up procedures. Hematoxylin & Eosin staining was applied to the sections in order to detect histopathological changes. Sections were examined and photographed under a light microscope. The routine streptavidin–biotin peroxidase complex method was used.In sheep with Jaagsiekte, tumoral foci with large and small acinar or papillary growths were observed in the alveolar and bronchiole lumens. The control group was negative for IL-1β, IL-6, IL-10 and IL-12β immunoreactivity. IL 1β-6-10 and 12β levels were dramatically increased in the Jaagsiekte group compared to the control group.It was determined that interleukins were produced from tumoral cells and tumor microenvironment elements, and these interleukins showed pro-inflammatory effects, except for IL-10.