Thomas Matthes obtained his medical degree, followed by a doctorate, at the University of Ulm in Germany in 1985. He then did a post-doctoral fellowship at the Institut Pasteur in Paris, where he worked in the field of autoimmunity. He arrived in Geneva in 1990 as a staff physician at the HUG, and subsequently completed FMH specialisations in internal medicine and haematology. In 2002, he was appointed Privat-Docent in the Department of Internal Medicine Specialties (now the Department of Medicine) at the UNIGE Faculty of Medicine, and in 2003 he became an associate physician in the haematology department at the HUG. His research focuses on the study of lymphocyte migration and the dissemination of lymphocyte tumour cells. He has also developed methods for multidimensional analysis of flow cytometry data. From 2005 to 2010, he was president of the Swiss Flow Cytometry Society, and in 2012 he founded the Swiss School of Flow Cytometry, of which he is the current director. He was promoted to associate professor at the Faculty of Medicine in April 2014, and retires in July 2025.