| 1962-1969 | Internship, residency, fellowship, and junior staff in medicine and nephrology, First Department of Medicine, The University of Tokyo, Faculty of Medicine |
| 1969-1971 | Research Associate, Department of Biochemistry, University of Pennsylvania, School of Medicine, Philadelphia, PA. |
| 1971-1974 | Senior fellow, Cedars-Sinai Medical Center and Department of Medicine, UCLA School of Medicine, Los Angeles, CA. |
| 1973-1974 | Assistant Professor of Medicine, Department of Medicine, UCLA School of Medicine |
| 1974-1977 | Associate Professor of Medicine, Department of Medicine, University of Southern California, School of Medicine, Los Angeles, CA. |
| 1977-1979 | Associate Professor of Medicine, Department of Medicine, UCLA School of Medicine |
| 1979-1985 | Professor of Medicine, Department of Medicine, UCLA School of Medicine |
| 1980-1985 | Chief, Nephrology Division, Wadsworth Veterans Administration Medical Center |
| 1983-1989 | Associate Professor of Medicine, Fourth Department of Medicine, The University of Tokyo, Faculty of Medicine, Tokyo |
| 1989-1996 | Professor and Chairman, First Department of Medicine, The University of Tokyo, Faculty of Medicine, Tokyo |
| 1996-2002 | Dean and Professor of Medicine, Tokai University, School of Medicine |
| 1997-present | Professor Emeritus, The University of Tokyo |
| 2002-2004 | Director and Professor, The Institute of Medical Science, Tokai University |
| 2003-2006 | President of the Science Council of Japan |
| 2004-2006 | Professor, Research Institute of Science and Technology, Tokai University |
| 2004-2007 | Adjunct Professor, the Research Center for Advanced Science and Technology, The University of Tokyo |
| 2005-2009 | Commissioner, Commission for Social Determinants of Health, World Health Organization |
| 2005-present | Chairman, Health Policy Institute, Japan |
| 2006-present | Member of President Council of the University of Tokyo |
| 2006-2008 | Science Advisor to the Cabinet; Science, Technology and Innovation |
| 2006 | Professor, National Graduate Institute for Policy Studies |
| 2009-present | Academic Fellow, National Graduate Institute for Policy Studies |