Therapeutic equivalence should be demonstrated in a randomised, reference-controlled multicentric double blind clinical trial with PRO 160/120, a combination of Sabal- and Urtica-Extract, and Finasteride, respectively, in patients suffering from benign prostatic hyperplasia (BPH, Stage I to II according to Aiken). The study involved 543 patients, who were treated for 48 weeks with two capsules of PRO 160/120 or one capsule of Finasteride per day, in a double dummy design. Primary variable was the change of the maximum urinary flow after 24 weeks of therapy in comparison to therapy start. As secondary variables urodynamic parameters such as average urinary flow, miction volume and miction time were monitored. Urinary symptoms were recorded by the International-Prostate-Symptom-Score (I-PSS, Paris 1993). Additionally, the impacts of the symptoms on quality of life had been assessed by a quality of life questionnaire according to The American Urological Association Measurement Committee (1991). An increase of the urinary flow rate could be observed in both treatment groups (1.9 ml/s with PRO 160/ 120; 2.4 ml/s with Finasteride). During the trial, the average urinary flow increased, whereas the miction time decreased in both groups in a similar extent. The miction volume did not show any relevant differences after treatment with either PRO 160/120 or Finasteride. The I-PSS decreased from 11.3 at the therapy start to 8.2 after 24 weeks and 6.5 (week 48) under PRO 160/120 and from 11.8 to 8.0 and 6.2, under Finasteride, respectively. Accordingly, life quality improved between therapy start and therapy end from 7.5 to 4.3 with PRO 160/120 and from 7.7 to 4.1 with Finasteride. In terms of safety aspects less adverse events occurred with the Sabal/Urtica-Extract as with Finasteride. Especially less cases of diminished ejaculation volume, erectile dysfunction and headache have been reported.