The present work aims to diagnose the causes of the death of 1.5-2 month-old rabbits kept in a personal subsidiary farm, with the study of pathomorphology, parasitological analysis of the contents of the caecum, and bacteriological examination of internal organs. The disease was characterized by a sporadic course among rabbits of 1.5-2 months of age from April to July. A striking clinical sign of the illness is gastric bloating, visualizing during a general examination. The death of the animal occurred 2-3 days after the manifestation of a clear clinical picture. The pathoanatomic autopsy showed flatulence and inflammation of the caecum and colon, hepatosis, lymphadenitis, acute dilation of the right lung, pulmonary edema. During the parasitological examination of the contents of the caecum, Eimeria oocysts were found. Bacteriological examination of internal organs demonstrated an association of S. saprophyticus microorganism with hemolytic properties and microscopic fungi of the genus Candida spp. The association of S.saprophyticus and Eimeria synergistic microorganisms can disrupt colonization resistance of the intestine, leading to intestinal dysbiosis in an organism with unformed immunity. Against the background of dysbiosis, Candida spp. yeast actively multiplies, affecting the course of the infectious process, resulting in an acute process and a combined form of infection. Thus, postmortem diagnosis of eimeriosis should be aimed at identifying the pathogen of eimeriosis and identifying associative microorganisms.