The green light potassium-titanyl-phosphate laser photoselective vaporization of the prostate is the latest modality for treatment of benign prostatic obstruction. Because of effective superficial tissue coagulation, intravascular absorption of fluid is minimal; therefore, development of transurethral resection syndrome is unlikely. To our knowledge, this is the first report of a patient undergoing photoselective vaporization of the prostate who developed full-blown transurethral resection syndrome because of intravascular absorption of sterile water. Absorption of hypotonic irrigant presumably occurred through the injury induced during insertion of the laser cystoscope.