OBJECTIVE To compare the effect of a Serenoa repens extract with placebo for symptoms of benign prostatic hyperplasia (BPH). PATIENTS AND METHODS In a double‐blind placebo‐controlled randomized trial between January 1999 and March 2000, 100 men with symptoms of BPH, aged < 80 years, with a maximum urinary flow rate of 5–15 mL/s for a voiding volume of 150 mL, were randomly and equally allocated to 320 mg S. repens extract or placebo (paraffin oil). The main outcome measures were the International Prostate Symptom Score (IPSS), peak urinary flow rate, and the Rosen International Index of Erectile Function (IIEF) questionnaire. RESULTS There was no significant difference between the treatments over the 12 weeks of the study in the IPSS, peak urinary flow rate or for the IIEF questionnaire. CONCLUSIONS During the trial all participants had some improvement in their symptoms of BPH but there was no significant beneficial effect of this S. repens extract over placebo in this 12‐week trial.