Mark Xavier Shanahan was one of the distinguished surgeons who pioneered the field of Cardiothoracic Surgery at St Vincent's Hospital Sydney from the mid 1950's. He was selected to join Harry Windsor on the Hospital staff in 1963, and together with Harry, perceived the talents of Victor Chang as a Resident Medical Officer, and had him appointed to the senior staff in 1972. Mark had a stellar career at school, being top of his class at St Joseph's College Hunters Hill, before entering Sydney University at the age of 15. He graduated with Honours at the age of 21, and undertook Residency training at St Vincent's Hospital in 1953. With Harry Windsor's encouragement, he took a position at St Helier Hospital London, leading to a position of Senior Surgical Registrar before working at St Francis Hospital, New York prior to returning to St Vincent's Hospital as an Honorary Cardiothoracic Surgeon in 1963. With Harry Windsor and Victor Chang, Mark pioneered many advances in cardiac surgery, including valve replacement, coronary artery surgery, early valve replacement for endocarditits, positive pressure ventilation for crushed chest injury, mechanical heart assistance and repair of defects following myocardial infarction. Mark was one of a group to first identify subacute heart rupture after myocardial infarction and correct this with excellent long-term survival. He also played a major role in the introduction of cardiac transplantation with Harry Windsor and Victor Chang. Mark was extremely gifted in many ways. He was a brilliant student. During his medical Residency he was a vocalist with a jazz band. He was also an excellent sportsman and at school was an A Grade cricketer and in latter years a low handicap golfer and senior surf ski champion. Mark was revered by those who worked with him. He never expected more of others than he did of himself. He was a superb teacher and wonderful mentor. He felt deeply for his patients, staff and colleagues, and often pressed their causes to the limit. His personal leadership built up nursing and paramedical teams with groups of cardiologists and anaesthetists, which formed a cardiac surgical service as good as any. Mark died of metastatic carcinoma of the thyroid. He was attended by St Vincent's Hospital staff throughout his long illness and, at his request went home to Merimbula from St Vincent's to be with his family and friends just days before his death. He is survived by his wife, Josephine. He had 4 children, Antoinette, William, Melanie (deceased) and Paul, and 8 grandchildren. His funeral occurred in Merimbula on August 14 attended by Australian and overseas colleagues, former patients, and friends from his local community. He will be remembered as a fine surgeon, a great colleague, role model and as a generous, thoughtful, dedicated and deeply spiritual human being.