E/Prof Roy read Medicine at the Christian Medical College, Vellore, India from 1967-1972, aided by a Government of India Cultural Scholarship. He returned to Singapore and trained from 1976 -1979 as a paediatrician at the National University of Singapore.

 
His sub-specialisation in Neonatology began in 1980 at the Kandang Kerbau Hospital, Singapore. He obtained additional training under the supervision of Prof Victor Yu at the Queen Victoria Medical Centre, Melbourne, in 1983 through a China Medical Board Scholarship of the University of Singapore.

From 1997 to 2005, E/Prof Roy was the Chief of the Department of Neonatology at the National University Hospital. In 2004, he was admitted as a Fellow of the Royal College of Paediatrics and Child Health Neonatal. Special and intensive care, newborn screening, well baby and child care, long term management of the congenital hypothyroid, developmental assessment and disorders and chairing the NUH Clinical Bioethics Committee form the sphere of A/Prof Roy's clinical practice.

Apart from that, E/Prof Roy also provides ad-hoc consultation on general paediatric ailments. Evidence, tempered with art, forms the basis of his practice. E/Prof Roy’s areas of academic and administrative responsibilities include directing undergraduate (faculty level) and postgraduate (departmental level) education and training in Neonatology, assisting in the development of an undergraduate Medical Ethics and Law curriculum and serving in the National Medical Ethic Committee and the Advisory Council for Neonatal screening. His research activities aim at improving medical education and in preventing mental and developmental retardation through providing a safe transition into the extrauterine environment and universal newborn screening for selected congenital conditions.