Dr Toh has been a Member of the Public Service Commission since 1992. He was appointed Associate Professor of medicine in 1970 and served as Vice-Dean of the Faculty of Medicine, University of Singapore , from 1969 to 1972. In 1972, he was elected President of the Asian-Pacific Society of Cardiology for 4 years. He served as Chairman of the National Medical Research Council from 1994 to 2000. Over the course of his career, he has contributed scientific publications to various local and international medical journals. He was awarded the Public Administration Medal (Gold) in 1970, the Public Service Star in 1999 and the Public Service Star (Bar) in 2009. Since April 2006, he is elected Chairman, Board of Trustees, National Cancer Research Fund.