Ralph Reader established the Department of Renal Medicine at Royal Prince Alfred Hospital in 1957 and in 1961 was appointed the the first Medical Director of the National Heart Foundation of Australia. Shortly after his return from Oxford in 1951, the RACP appointed him Honorary Secretary of the inaugural editorial committee of its newly established Australasian Annals of Medicine (now Internal Medicine Journal.) From 1975 to 1982 Ralph was Chairman of the first World Health Organization/International Society of Hypewrtension (WHO-ISH) Liaison Committee for Mild Hypertension.

Ralph was appointed in 1940, with three of his colleagues, as Students in Residence at Royal Prince Alfred Hospital to relieve the wartime shortage of resident doctors. He graduated in 1940 and in 1941 was appointed Professorial Resident Medical Officer to the clinical professors at the Hospital. He enlisted in 1941 and was mobilised in 1942. Until 1946 he served as a Surgeon Lieutenant and acting Lieutenant Commander and Medical Specialist with the Royal Australian Naval Volunteer Reserve(RANVR.)

After World War II he returned to the University of Sydney and took up a research scholarship within the Department of Medicine. During his war service he had developed an interest in the pathogenesis of acute glomerulonephritis and the causes of nephritis. He applied to Professor Lambie to develop these interests within his department.

From 1948 to 1950 he was a Nuffield Dominions Fellow within the Department of Medicine at the University of Oxford. Working with Professor Witts at the Radcliffe Infirmary, Ralph had the opportunity to investigate "the popular concept that rheumatism was pathogenetically related to environmental chilling and tissue temperature changes." He received his DPhil for this work in 1952.

While still in Oxford, Ralph was appointed Honorary Assistant Physician at Royal Prince Alfred Hospital (RPAH) and on his return in 1951 began clinical duties, student tutorials, and fourth year lectures in nephrology as well as research in Professor Lambie's laboratory into the role of complement in immunological diseases such as acute and chronic glomerulonephritis. At the same time he set up practice in Macquarie Street (and later in the Medical Specialist Centre established adjacent to RPAH) and remained active as a consultant for the next ten years.

In his final three years at RPAH he was promoted to Acting Physician in Charge of one of the six Medical Units. Ralph channeled his interest in renal disease into the establishment of the 'Renal Group.' With his leadership this voluntary group "sought out interesting cases, consulted when requested and introduced the advances in diagnostic and therapeutic methods that were rapidly evolving". When Ralph resigned from Royal Prince Alfred Hospital, John Sands took over the leadership of this 'Group.'

However, Ralph's flair for leadership in clinical practice and research had been recognised and in 1961 he was invited to join the National Heart Foundation as Medical Director, an appointment he accepted. He was keen to direct a "community based and funded health organisation promoting research, professional and community education and rehabilitation in cardiac disease". He also saw this as an opportunity to conduct his own research and further develop his understanding of hypertension within a different context. Ralph remained Medical Director until 1971, at which time he became Director and CEO, finally retiring from the Foundation in 1980.

Under his stewardship the National Heart Foundation strove to initiate programs that addressed the control of risk factors like high cholesterol, smoking, and hypertension as well as the educating the community about coronary care, signs of heart attack, heart-lung resuscitation and cardiac rehabilitation.

On his retirement from the Foundation, The Cardiac Society of Australia and New Zealand established the Ralph Reader Young Investigator Prize in recognition of his concern for young Research Fellows fostered by the Foundation. The prize has been awarded annually since 1981.

As well as chairing the WHO-ISH committee on Mild Hypertension, Ralph conducted many assignments for WHO, including a tour of South East Asia investigating rheumatic heart disease in 1968, a survey of therapeutic trials in mild hypertension in USA, Europe, England and Australia in 1973, a review of prevalence and control of hypertension in India in 1981, and attended many international WHO conferences on cardiovascular problems, sometimes acting as rapporteur.

In 1976 Ralph was made a companion of the Order of St Michael and St George for his services to medicine.