Coccidiosis is one of the most important diseases that attack the poultry industry. This disease is an intestinal disease caused by protozoan parasites from the genus Eimeria. The aim of this case report was to establish a diagnosis of mortality in a broiler chicken aged 21 days. The broiler chicken was obtained from a poultry in Kubu, Bangli Regency, Bali with a population of 12.000 broiler chickens. The number of sick chickens was 145 and 37 diede with the same symptomps within seven days. Based on these data, epidemiological data were obtainded which consisted of 1,20% morbidity; 0,30% mortality; and 25,51% case fatality rate (CFR). The broiler chicken was obtained from a poultry in Kubu, Bangli Regency, Bali with a population of 12.000 broiler chickens. The number of sick chickens was 145 and 37 diede with the same symptomps within seven days. Based on these data, epidemiological data were obtainded which consisted of 1,20% morbidity; 0,30% mortality; and 25,51% case fatality rate (CFR). The chicken was taken to the Veterinary Pathology Laboratory for necropsy. Pathological changes are seen in the hemorrhagic intestine and the hemorrhagic cecum dan mucosal erosin. Furthermore, changes in the histopathology of the cecum include hemorrhage, necrosis, and inflammatory cell infiltration. In addition, the schizont stage was also found. The finding of schizont generation in the cecum indicates coccidiosis infection in chickens. Then, qualitative and quantitative stool examination was carried out. Qualitative examination was carried out using native, sedimentation and buoyancy methods. Quantitative examination with the Mc.Master method to determine the intensity of infection. The results of the qualitative examination found oocysts and oocysts that had sporulated. While quantitatively obtained the number of oocysts as much as 18750/gram. Based on clinical symptoms, blood smear examination, changes in anatomical pathology, histopathology, and stool examination, it can be concluded that case chickens have coccidiosis caused by Eimeria tenella. It is necessary to conduct further studies regarding the assistance of Eimeria spp. in broiler chickens.