Since preparations from ileum are used for experimental pharmacological investigations this study examines the effects of the neurotransmitters acetylcholine, serotonin and histamine on peristaltic activity of gut from mice and guinea pigs. In addition the effects of some plant extracts (peppermint, camomile and angelica root) commonly used in phytotherapy for gastrointestinal diseases are studied. Longitudinal smooth muscle strips of the distal ileum of both species are mounted in a perfused organ bath and contractions are recorded under isometric conditions. The effects of the transmitters (10–5 M) and the plant extracts (diluted 1:100) on amplitude and frequency are evaluated. The transmitters interact in peristaltic contractility in different ways: In mouse ileum acetylcholine induces initially a strong tonic contraction, serotonin shows a weaker reaction whereas histamine has no measurable effect on the peristaltic activity; in guinea pig ileum acetylcholine generates also a strong tonic contraction, similarly histamine. Administration of the herbal extracts shows that they are able to inhibit the neurotransmitter-induced contractions. Ileum from mouse and guinea pig shows different properties when investigated in vitro, however, spasmolytic effects of different plant extracts could be observed in both models. Supported by A. Teufel-Stiftung