The 2 patients were both aged females with medical history of diabetes mellitus. The chief complaints were both hyperpyrexia. Laboratory tests presented markedly elevated white blood cells and C-reactive protein, indicating severe systemic infections. Urine culture confirmed the growth of Escherichia coli. CT scan revealed thickened bladder wall with intraluminal and interstitial collections of gas. After the diagnosis of emphysema cystitis was established, conservative treatments including bladder drainage, strict glycemic control and sensitive antibiotics were administered timely. Both of the 2 patients got fully recovery after standard treatment.