Xanthohumol (1), isolated from hop, was fed to rats in a dose of 1000 mg kg(-1) body weight. The faeces of the animals were collected after 24 and 48 h and analysed for metabolites of 1. Approximately 89% of the recovered flavonoid-compounds consisted of unchanged 1. Sixteen metabolites and six previously known metabolites were isolated and characterized by coupling techniques (HPLC-NMR, HPLC-MS and HPLC-DAD). Their structures were elucidated by spectroscopic methods, especially using NMR spectroscopy. Twenty metabolites had a modified chalcone structure and two metabolites were flavanone derivatives.