A 69-year-old man received transurethral resection (TUR) ofbladder tumor. The histopathological diagnosis was urothelial carcinoma, high grade, pT1＋pTis. The surgical specimens obtained by second TUR showed no residual malignancy histopathologically. Intravesical Bacillus Calmette-Guerin (BCG) instillation therapy was initiated 2 months after the second TUR. He complained of lower abdominal pain and painful urination on the day following the second instillation of BCG. Computed tomography and cystography demonstrated rupture ofthe urinary bladder. During 2 weeks ofconservative treatment, the symptoms persisted. Then, open repair ofthe bladder was performed. Intravesical BCG therapy has been a widely accepted treatment for bladder cancer with high grade Ta and T1, and carcinoma in situ. In the present case, thinning ofthe bladder wall, delayed wound healing caused by 2 TURs, and abdominal pressure may have been the factors leading to the bladder rupture in addition to inflammation of the bladder due to BCG instillation. Although bladder rupture caused by intravesical BCG therapy has not been reported, we must be aware ofthe possibility ofthis rare condition, especially after 2 consecutive TURs.