Nick Day is Director of the Wellcome Trust Mahidol University Oxford Tropical Medicine Research Programme. In 1992 Nick Day left Oxford to direct the nascent Wellcome Trust Tropical Medicine Research Unit in Ho Chi Minh City, Viet Nam. Over the next four years conducted pivotal work on the pathophysiology and treatment of malaria, typhoid, tetanus and dengue and the Vietnam Unit became established as a regional centre of excellence. He was the first to measure renal blood flow in sepsis, and to characterise the haemodynamic and metabolic responses to dopamine and adrenaline in sepsis and malaria. He also directed the then largest randomised controlled trial in severe malaria, comparing artemether with quinine in over 500 patients, and also the first randomised trial of renal replacement therapies showing, not only that haemofiltration reduced mortality, but also that it was less expensive. After a brief period in Oxford he returned to Asia to take over the Directorship of the programme in Thailand, where he has initiated and supervised important work on melioidosis, leptospirosis, scrub and murine typhus and cryptococcal meningitis.