Vijay Kakkar, professor of surgical science at King’s College School of Medicine and Dentistry, established the importance of giving the anticoagulant heparin to surgical patients, saving thousands of lives by preventing fatal blood clots. He was born in Sialkot in the Punjab, India on 22 March 1937. His father, Harbhagwan Kakkar, was a doctor; his mother was Lilavathi Kakkar. In 1955, he began studying medicine at the Gandhi Medical School in Bhopal and qualified in 1960. After a year as a house doctor at the Irwin Hospital in Delhi, he went to the UK, where he held junior posts. In 1964, he was appointed as a lecturer in the Nuffield department of surgery, University of Oxford. In 1965, he first went to King’s as a Pfizer research fellow and honorary senior registrar. He stayed at King’s, as a lecturer and honorary senior registrar, senior lecturer and honorary consultant, and (from 1975), professor and director of the thrombosis research unit. From 1990 to 2009, he was also director of the Thrombosis Research Institute, which he founded. When he retired in 2006 he opened a second thrombosis research institute in Bangalore, India. As a registrar at King’s he became aware of the large number of surgical patients dying from pulmonary embolism. He began researching groups at risk of embolism and, with E T Yin and Stanford Wessler, who were researching heparin as a prophylactic to prevent leg clots, established that low molecular weight heparin was the most effective form of the drug. Kakkar organised a randomised controlled trial at 28 treatment centres, showing that prophylactic heparin saved seven lives in every 1,000 patients undergoing surgery. The results of the trial were written up in a ground-breaking paper in *The Lancet* ‘Prevention of postoperative thromboembolism’ (*The Lancet* 1975 306 [7924] 63-64). He was a prolific author and wrote 680 articles and six books. Kakkar was the founder president of the British Society for Haemostasis and Thrombosis and of the South Asian Society on Atherosclerosis and Thrombosis. He received many awards, including a Hunterian professorship at the Royal College of Surgeons (in 1969), a lifetime achievement award from the International Union of Angiology and, in 2010, an OBE. In 1962, he married Savitri Karnani, whom he had met at medical school. They had two sons and four grandchildren. His son, Ajay Kumar Kakkar, Baron Kakkar, became professor of surgery at University College London. Vijay Vir Kakkar died on 5 November 2016. He was 79.