| 1875: | Born 2 January, in Copenhagen; son of Johan Jansen (a barber) and Emma Emilie née Jensen. Attended Borgerdyd Grammar School. | |
| 1900: | Graduated in medicine from Copenhagen University. | |
| 1901-06: | Assistant at the Finsen Institute, and registrar at the Municipal Hospital (Kommunehospitalet), the Vestre (Prison) Hospital and the Fever Hospital (Blegdamshospitalet), all in Copenhagen. | |
| 1906: | Married Gerda Rønning (b. 1875, daughter of Poul Christian Rønning, manufacturer, and Anna Petra Kristine, née Jensen). | |
| 1906: | Doctoral thesis: Experimental studies on the mode of action of the Finsen treatment (In Danish). | |
| 1906-07: | Assistant at Cardiology Department, St. Joseph’s Hospital, Copenhagen. | |
| 1907-12: | Registrar at Medical Department II, Municipal Hospital, Copenhagen. | |
| 1912-13: | Responsible for Department of Hydrotherapy, Municipal Hospital, Copenhagen. | |
| 1913-33: | Head of the Department of Hydrotherapy and Massage, Bispebjerg Hospital. | |
| 1913-15: | President of Danish Society for Physical Therapy. | |
| 1914-16: | Private teacher (Privatdocent), Physiotherapy. | |
| 1918: | Specialist in internal medicine (especially arthritis, cardiology and physiotherapy). | |
| 1909-23: | Consultant at Rosenborg Brøndanstalt (Thermal Cure Hospital). | |
| 1918-20: | 2nd term as President of Danish Society for Physical Therapy. | |
| 1923-28: | Consultant at the Emanatorium of the Radium Station, Copenhagen. | |
| 1932: | Awarded Belgian Ordre de la Couronne. | |
| 1933: | Died, 30 June. | |
Hans Ditlev Jansen
Jansen was hardworking, well liked by his colleagues, upright and helpful as a chief, and enjoyed teaching. His primary interest was rheumatology, and he wrote a physiotherapy textbook. He promoted the establishment of a Rheumatology Sanatorium at Skælskør (Andelsforeningernes Gigtsanatorium) supported by the Cooperative Societies, advised the planning of the Institute of Physiotherapy at the Karolinska Sjukhuset, Stockholm, and represented Denmark in the Ligue Internationale Contre le Rheumatisme (now called the International League Against Rheumatism – ILAR).