Abstract: Due to an increase in phosphorus uptake root colonization by symbiotic arbuscularmycorrhizal (AM) fungi often lead to beneficial effects on plant growth. Focussing the plant rootsthis study was carried out to analyse whether the biomass growth of Valeriana officinalis(valerian), Angelica archangelica (archangel) and Glycyrrhiza glabra (liquorice) could beenhanced through the AM symbiosis. For that purpose two clones per species of in-vitropropagated plants were tested with several AMF species. The AM root colonization of themedicinal plants was high in all treatments inoculated with AMF. Generally the P nutrition ofAM plants was improved, but the effects on the root biomass were diverse.