Functional gastro-intestinal diseases such as functional dyspepsia and irritable bowel syndrome are a therapeutic challenge, as they are not only characterized by a multitude of symptoms, some of them with severe consequences for affected patients, but are also caused by a multitude of factors. The clinical efficacy of the therapeutics STW 5/Iberogast in these diseases has been proven in a number of randomized prospective clinical studies. Several preclinical studies suggest that its efficacy could be due to its complex composition of nine standardized herbal extracts, which act differently on multiple sites. This principle, which is quite popular in clinical medicine, was introduced as a multi-target therapy for functional bowel disorders. Components of STW 5/Iberogast reduce gastro-intestinal hypersensitivity and act spasmolytic on spastic, tonicising on atonic gastro-intestinal muscle. In addition a stimulating effect on reduced mucus-secretion, an inhibitory effect on enhanced gastric acid secretion and an anti-inflammatory effect have been shown. These effects could explain the clinical efficacy of STW5/Iberogast in a large range of symptoms.