John Loewenthal was born on 22 December 1914, at Bondi, New South Wales, the son of Abraham Marcus Loewenthal, who worked with the Australian Mutual Providence Society, and of Carlotta Minnie. He was educated at Sydney Grammar School from 1925 to 1931 and was school captain in his last year. He then studied medicine at the University of Sydney, graduating in 1937, and was a prize winner in medicine and psychiatry. After early resident appointments in Sydney he was in the Royal Australian Army Medical Corps from 1939 to 1946, serving in Australia, the Middle East and the South West Pacific. In New Guinea he was in charge of a mobile surgical unit which had to work in primitive conditions. Whilst serving with the 113th Australian General Hospital he met and married June, daughter of Dr James Stewart of Maitland, New South Wales, in 1944. Before his demobilization, he passed the MS, Melbourne, and received the Efficiency Decoration at the end of his military service. Shortly after returning home he was awarded a Nuffield Travelling Fellowship which brought him to England. After passing the Primary FRCS at St Bartholomew's Hospital Medical College he completed the Final Fellowship six months later whilst serving in a registrar and research post on the surgical unit of James Paterson Ross. He spent a further year with Michael Boyd at Manchester and gave a Hunterian Lecture on venous ulceration of the leg in 1948. On returning to Sydney in 1949 he was appointed assistant surgeon to the Royal Prince Alfred Hospital and became consultant surgeon to the Australian Army HQ in the following year. After seven years in private practice the Bosch Chair of Surgery fell vacant at Sydney University and after much thought and hesitation, he applied for and succeeded Harold Dew in this post. Loewenthal was a most capable technical surgeon, but his administrative ability resulted in his rapid academic advancement and then in office at the Royal Australasian College of Surgeons. He was Dean of the University Faculty of Medicine, 1966-71, and a Fellow of the Senate of Sydney University. He served on the Council of the RACS 1960-74 and was President 1971-74. John Loewenthal admired his professional predecessor, Harold Dew, who had struggled with a near impossible wartime task when the number of medical undergraduates had enormously increased and staff were in short supply. Loewenthal succeeded to these overwhelming teaching commitments at St Vincent's and the Royal North Shore Hospitals as well as at the Royal Prince Alfred. In due course, whilst serving as Dean of the Faculty of Medicine, he saw some of his own young men succeed to surgical chairs at St Vincent's and Royal North Shore, and then at the Veteran's Hospital. Having set his university fiefdom in better order he directed his energies to the work of the Royal Australasian College of Surgeons where he played a major part in reorganising the examination system. At the same time he made a considerable contribution to the development of the Royal Prince Alfred Hospital, successfully collecting funds for building and research and for the improvement of postgraduate training. A man of great energy and determination, whilst indefatigably pursuing his objectives, he always maintained his sense of humour and sound judgement. He was a loyal supporter of his juniors and a generous excuser of the foibles of his seniors. Outside his university and college activities he was a most industrious supporter of the Heart Foundation of which he was President at the time of his death. He was also a member of the National Health and Medical Research Council and of the Life Insurance Medical Research Fund. During 1971 he served as a highly successful Sir Arthur Sims Travelling Professor, visiting Hong Kong, Canada and the United Kingdom. He was awarded the honorary fellowships of a number of overseas surgical colleges and one honour which gave him especial pleasure was the award of honorary perpetual studentship at St Bartholomew's Hospital Medical College, a distinction which he shared with the late Duke of Windsor. Apart from a Hunterian Professorship, he was also a Moynihan Lecturer and gave many other eponymous lectures. He was made CMG in 1976 and Knight Bachelor in 1978, coming to England for his investiture. Shortly before his retirement his surgical colleagues decided to show their appreciation at a farewell dinner in the Great Hall of the University of Sydney. The dinner was held on 17 August, 1979 but, just after his own health had been proposed, he was struck down with symptoms of massive cardiac infarction. Emergency aid was prompt and he was admitted to the Royal Prince Alfred Hospital where, having improved for a few days, he developed signs of perforation of the interventricular septum. Despite the skilled attention of his colleagues he died on 25 August, 1979 just eight days after his farewell dinner. He was survived by his wife, two sons and two daughters.