A case of bladder explosion with wide rupture during transurethral resection of the prostate (TURP) is reported. Immediate cystography was performed and the patient was promptly operated; the postoperative course was uneventful. Intravesical explosion is caused by explosive gas formation and the more dangerous combination is the mixture of air and hydrogen; therefore, the introduction of air during TURP is necessary in order to produce a bladder explosion. This unusual complication of a common urological procedure is rare but serious, and should it arise always requires immediate surgical correction.