Harald Hoensch received his MD degree from the university of Frankfurt/Germany and his Dr.med. title also in Frankfurt. He was trained and got his medical state board at the university of Erlangen/Germany. 1969 he obtained the license to practice as a medical doctor and was further working in internal medicine and gastroenterology in Erlangen. He became a board certified specialist in internal medicine and gastroenterology. From 1973-1975 he joined Professor Rudi Schmid at the university of California in San Francisco/USA and did research work on the role of drug-metabolising enzymes in the gut and established its dependency on dietary iron. His work was published in the leading journals of gastroenterology. He continued his studies on cytochrome P-450 in clinical GI-disorders in his lab at the university of Tuebingen/Germany and received his venia legendi.From 1982-1985 he was deputy chief of general medicine in Essen/Germany. From 1985-2006 he was clinical director of internal medicine in a comunity hospital near Frankfurt. He is now practicing gastroenterology in his private practice in Darmstadt/Germany. He retired from his clinical duties Dezember 2015.