Serenoa repens is one of many herbal products used to treat benign prostatic hyperplasia. The treatment has been studied extensively, but the methodological quality has often been poor. Metaanalysis of early studies indicate that the treatment may have favourable effects on patients with benign prostatic hyperplasia, but more recent investigations of better methodological quality have questioned these results. The available documentation does not support use of products containing serenoa repens for these patients. Serenoa repens is associated with mild adverse effects comparable to that of placebo.