OBJECTIVE Emphysematous cholecystitis (EC) is an uncommon, severe variant of acute cholecystitis caused by gas- forming bacteria - most often Clostridium perfringens and Escherichia coli. We present a deceptive case of EC associated with retroperitoneal gas gangrene and emphysematous pancreatitis. METHODS An 86-year-old, overweight woman was admitted to the emergency department with non-specific abdominal symptoms. Admission laboratory tests showed elevated diastase levels indicating acute pancreatitis. Computed tomography (CT) demonstrated a substantial amount of gas in the retroperitoneum and peritoneal cavity, which raised a suspicion of duodenal perforation. Primary diagnosis was not confirmed during emergency laparotomy, which revealed a gangrenous gallbladder adjacent to the duodenum and surrounded by purulent fluid. The final diagnosis established after laparotomy and rereading of CT scans was that of emphysematous cholecystitis associated with gangrenous pancreatitis and retroperitoneal gangrene. After surgery, the patient was transferred to the intensive care unit in septic shock. Shortly after, the second laparotomy was undertaken on suspicion of internal bleeding. During surgery, the patient experienced cardiac arrest and died despite immediate resuscitation. CONCLUSIONS Emphysematous cholecystitis may be associated with a spread of infection both to the peritoneal cavity and retroperitoneum and result in a substantial amount of gas in those anatomic compartments. The knowledge of this rare complication may be helpful in establishing a correct diagnosis.