Crocodile farms are getting popular in Bangladesh in an economic point of view. In one of the farms, some crocodiles were found sick and three of them died between May and July in 2006. This investigation was performed to diagnose the cause of the death. Routine postmortem examination was conducted. Samples were collected in 10% neutral buffered formalin for histopathology and in falcon tube for microbiological study. Additional swabs were collected in nutrient broth. Histopathological and microbiological studies were conducted using routine procedures. In addition Giemsa, Gram and PAS stains were performed to detect the organism in tissues. Grossly, esophagus, trachea, lungs, liver, spleen, heart and kidney were congested. Intestine, rectum and colon were hemorrhagic. Clay colored material was found in colo-rectum. Purulent exudates in lungs and thick and cloudy pericardial fluid in pericardial sac were found. Histologically, multifocal granulomatous inflammation was evident in lung, liver, kidney, intestine and colon with bacterial colonies, fungal spores and hyphae. These bacteria were appeared as Gram negative. Fungal hyphae and spores were detected in liver, lungs and colon by using PAS stain. Bacteriologically, E. coli were isolated from lungs exudates, pericardial fluids and intestinal fluids. Therefore, it can be concluded that 3 crocodiles died due to E. coli septicemia concurrent with mycotic infection.