Xenografts of human benign hyperplastic prostate tissue (BPH) have been established as a model for the investigation of the etiology of BPH. In this paper it is our aim to answer the question of whether this model is useful for the established therapy of the disease. Additionally we try to evaluate the value of a commonly used plant extract for the therapy of BPH. Is there any influence of the extract from Sabal serrulatum on the BPH tissue in our model? Human BPH tissue from 2 patients was transplanted into athymic nude mice and treated with three different regimens. Animals of group I did not receive any treatment and served as control, in groups II and III the tissue was stimulated by application of silicone tubes containing crystalline 5 alpha-dihydrotestosterone and estradiol. Animals of group II additionally were treated orally with the lipophilic extract of S. serrulatum (contained in Prostagutt N), which is commonly used for the treatment of BPH clinically. Significant inhibition of tissue growth was observed in group III when compared to group II. In group I (control) atrophy of the graft was observed as expected. However, histologically no differences were visible between groups II and III. Our experiment shows a significant growth-inhibiting effect of the plant extract for human BPH tissue in our model (p less than 0.05). We conclude that the nude mouse model can be useful for the evaluation of systemic therapy modalities of human BPH and that the plant extract may have a certain value for clinical treatment, which is not only due to subjective criteria.