In this study, we aimed to evaluate the oxidative damage caused by lipid peroxidation due to renal coccidiosis by histopathological and immunohistochemical methods. Material-The material of this study was made up of tissue samples taken from 139 geese whose average age was 10 weeks, who were brought to our department dead between 2013-2020. 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.Various clinical signs such as fever, respiratory distress, weakness, anorexia, tremors, inability to get up from the ground, balance disorders, rotational movement, diarrhea, wheezing were detected in geese. In systemic necropsies of geese, large and small white nodular structures were detected in the kidney. In histopathological examinations, coccidiosis agents (E. truncata) were found in the tubular epithelium of the kidney. Necrosis and mononuclear cell infiltration were observed in the tubules due to the presence of E. truncata. In addition, edema and hyperemia in the lungs, multifocal necrosis in the liver, cell infiltration in the portal spaces and enteritis were other important histopathological findings. In one case, aspergillosis was detected together with renal coccidiosis. We observed that MDA expression was more severe in oocyst stages, which is the mature form of the parasite, compared to other parasitic life stages.Based on the results obtained from this study, it was revealed that renal coccidiosis in geese caused lipid peroxidation / oxidative damage through the increase in MDA expression.