Ultrasound-guided renal cyst puncture of 69 renal cysts was performed in our department, between April, 1986 and March, 1992. The indications for this procedure consisted of cysts over 4 cm in diameter and those of less than 4 cm in diameter with caliceal or pelvic distortion and compression. Fifty-four cysts were instilled with dehydrated ethanol, 10 cysts with minocycline, one cyst with 50% dextrose as a sclerosing agent, and four cysts underwent only aspiration of the cyst fluid. We instilled dehydrated ethanol when the aspirated fluid was not bloody and there existed no extravasation of the contrast medium or communication between the cyst cavity and the urinary tract. The instilled volume of dehydrated ethanol ranged from 8 to 400 ml (average: 72.8 ml), equivalent to 35.0-100% (average: 62.1%) of the aspirated volume. Retention time was 20 minutes, the follow-up period was 2-67 months (mean follow-up period: 13.7 months), and the reduction rate of the cyst volume was 60.0-100% (average: 96.2%). There were no major complications due to puncture or dehydrated ethanol instillation. Ultrasound-guided renal cyst puncture was shown to be a safe non-surgical approach and a useful method of treating renal cysts.