Introduction: Emphysematous cystitis is a rare form of acute infection of the bladder which most cases are seen in diabetic patients. Most infections are due to E.coli and Klebsiella species. Predisposing factors are diabetes mellitus, recurrent urinary tract infections, bladder outlet obstruction and neurogenic bladder. CT-scan is the most sensitive method of diagnosis that detects air within intramular of bladder that is patogonomonic of the disease. In this case report we reported two cases of emphysematous cystitis.Cases: The first case was a 73 years old diabetic women who was admitted due to acute renal failure after cholecystectomy. During hospitalizotion, after remission of renal function, she developed fever, abdominal pain, hematuria and progressive abdominal distention. In physical examination she had generalized abdominal tenderness with dominance in the lower abdomen without rebound tenderness which with observation of air in intramural bladder by CT-scan, diagnosis of emphysematous cystitis was confirmed and the patient was treated and improved. The second case was a 37 years old diabetic women. She was reffered to the hospital because of nausea, recurrent vomiting and abdominal pain. In physical examination she had severe hypotention, generalized abdominal tenderness that was dominant in the lower abdomen and abdominal mass in suprapubic area. Suspicious to emphysematous cystitis, pelvic CT-scan was ordered. By observation of air in intramural bladder, emphysematous cystitis was confirmed. Patient was treated with antibiotic, insertion of fouly catheter and was improved. Conclusion:Undiagnosing or delaying in initiating appropriate treatment can lead to peritonitis secondary to intraperitoneal perforation of the bladder, septisemia and ultimately death of the patient. Timely diagnosis and aggressive therapy are important for the survival of these patients.