| 2010 | Clinical Advisor, Laboratory of Biomedical Engineering, Cornell College of Engineering, Cornell University |
| 2002~ | Director, Leukemia and Myeloproliferative Center, New York Presbyterian Hospital |
| 2002~ | Professor of Medicine, Cornell University Medical College |
| 1973~ | Attending Physician, New York Presbyterian Hospital |
| 1973-2002 | Clinical Professor of Medicine, Cornell University Medical College |
| 1967-1973 | Associate Clinical Professor of Medicine, Cornell University Medical College |
| 1967-1973 | Associate Attending Physician, New York Presbyterian Hospital |
| 1964-1967 | Assistant Attending Physician, New York Presbyterian Hospital |
| 1963-1966 | Assistant Visiting Physician 2nd (Cornell) Med. Div., Bellevue Hospital |
| 1962-1967 | Assistant Clinical Professor of Medicine, Cornell University Medical College |
| 1958-1964 | Physician to Outpatients, New York Presbyterian Hospital |
| 1958-1962 | Instructor in Medicine, Cornell University Medical College |
| 1958-1959 | Visiting Fulbright Lecturer, University of Bahia School of Medicine, Bahia, Brazil |
| 1956-1958 | Assistant in Medicine, Cornell University Medical College |