Since the start of his scientific career he has worked with steroid hormones. His main focus was their metabolism and excretion (in domestic livestock) and the development of noninvasive methods for their quantification (mainly in the faeces, but also in saliva and urine). To obtain these objectives he conducted several externally funded projects. Since the habilitation his main research focus has been the metabolism and excretion of glucocorticoids, the characterisation of their metabolites in faeces, as well as the development and validation of EIAs for their quantification. He and his coworkers succeeded in establishing the world-wide first non-invasive method for stress-assessment in animals by measuring faecal glucocorticoid metabolites. Their assays are now applied successfully in an increasing number of bird and mammalian species in a variety of research fields such as animal welfare but also in ethological, ecological or biomedical studies. Recently, he has started studies to clarify the source and metabolism of glucocorticoids in hair samples, but he has also been involved in many projects measuring salivary glucocorticoids. Rupert Palme has published ~400 peer reviewed papers