We present here a case report of a seminal vesicle cyst (SVC) in a young man with epididymal tissue in a dysgenetic kidney and ectopic ureteral insertion. SVCs are usually found in the second to fourth decades of life. SVCs can be congenital or acquired. Congenital SVCs seem to be invariably associated with renal dysplasia, hypoplasia, agenesis and duplication abnormalities in the same side, with the exception of two cases [1,2].We report here a case report of a 26-year-old man who was referred to our hospital owing to absence of the left kidney, identified by sonography during a health examination. Magnetic resonance imaging (MRI) and magnetic resonance urography (MRU) showed a cyst expanding from the kidney fossa to the seminal vesicle fossa instead of the left kidney, ureter and seminal vesicle (Figure 1). His right urinary tract was normal. A solid mass was present in the left side of the bladder, and the left ureteral orifice could not be seen with a cystoscope. Laboratory tests of the blood and urine were normal. Clinical examination showed that the patient had a normal pair of testes, epididymis and penis.The surgeons performed a retroperitoneoscopy together with a small inclined inferior abdominal incision under general anaesthesia. At first, the patient was recumbent on his right arm. The cyst was resected in the postperitoneal region. There were three laparoscopic ports: a 12-mm trocar port at the left postaxillary line below the 12th rib, a 5-mm trocar port at the preaxillary line and 2 cm above the spina iliaca and a 10-mm trocar port at the preaxillary line below the arcus costarum. During the operation, the surgeons noticed that the cyst was just as shown by MRI and MRU. There were no vessels to the left kidney. The cyst was dissociated easily. The ectopic ureter opened in the seminal vesicle cyst, which was filled with chyliform fluid. At first, the surgeons suspected that the fluid was liquor puris, but it was later found to be semen with few sperm, which had poor vitality. Thereafter, the patient was moved to the Trendelenburg position. A small inclined inferior abdominal incision was made at the left lateral border of the rectus muscle. This cyst was resected completely.The total operating time was 120 min, with an estimated blood loss of 100 mL. The patient was able