Phytotherapy of BPS has a long tradition in Germany; nevertheless, data referring to single phytotherapeutic agents are rare. We therefore performed a randomized, double-blind, placebo-controlled multicenter study for 1 year with Bazoton uno (459 mg dry extract of stinging nettle roots) with 246 patients. The IPSS decreased on average from 18.7+/-0.3 to 13.0+/-0.5 with a statistically significant difference compared to placebo (18.5+/-0.3 to 13.8+/-0.5; p=0.0233). The median Q(max) increased by 3.0+/-0.4 ml/s in comparison to 2.9+/-0.4 ml/s (placebo), thus not statistically significantly different, as well as the median volume of residual urine, which changed from 35.5+/-3.4 ml before therapy to 20.0+/-2.8 ml and from 40.0+/-4.0 ml to 21.0+/-2.9 ml under placebo application. The number of adverse events (29/38) as well as urinary infections etc. (3/10 events) was smaller under Bazoton uno therapy compared to placebo. Treatment with Bazoton uno can therefore be considered a safe therapeutic option for BPS, especially for reducing irritative symptoms and BPS-associated complications due to the postulated antiphlogistic and antiproliferative effects of the stinging nettle extract. A strong increase of Q(max) or reduction of residual urine are not to be expected.