Since October 1990, 414 patients with micturition complaints due to benign prostatic hyperplasia were treated with transurethral microwave thermotherapy (TUMT). In this study 130 patients are presented who were treated according to a strict protocol. The technique of treatment as well as the inclusion and exclusion criteria for TUMT treatment are discussed. With a follow-up period of 1 year after TUMT, a clear subjective improvement was seen in 63% of the patients. Objective improvement, however, is less pronounced. The main complication of TUMT is a urinary retention, which can be treated with a transurethral catheter. This catheter can be removed in most patients after 1 week.