Between June 1997 and September 1999, we performed transurethral unroofing (TUUR) in three patients with hematospermia that recurred repeatedly for one year or more. Patient 1 (48 years old) and Patient 2 (59 years old) were diagnosed as having müllerian duct cysts that communicated with the left ejaculatory duct, and Patient 3 (36 years old) as an ejaculatory duct obstruction with the right ejaculatory duct dilation. A mixture of water-soluble contrast medium and indigocarmine blue dye was injected into the cysts and the ejaculatory duct cavity after incision of the vas deferens in Patients 1 and 3, and by cyst puncture under transrectal ultrasound (TRUS) guidance in Patient 2. Then the urethra was incised between the bladder neck and the verumontanum using a Collins' hot knife electrode, and spouting of the dye from the incision was judged to indicate successful unroofing. In Patient 2, safe and simple TUUR was possible by identifying the cyst location and its distance from the knife electrode under TRUS guidance. Hematospermia resolved after surgery in all three patients and there has been no recurrence for 1.3-3.5 years (mean: 2.6 years). Thus, TUUR was effective for treating chronic hematospermia caused by müllerian duct cyst and ejaculatory duct obstruction. For safe and reliable performance of this treatment, TRUS guidance and injection of the dye into the cyst and ejaculatory duct cavity can be recommended.