After training in internal medicine, nephrology and epidemiology, Dave Sackett's first career (age 32) was as the founding Chair of Clinical Epidemiology & Biostatistics at McMaster. In his second career he began to design, execute, interpret, monitor, write and teach about randomized clinical trials, an activity that continues to the present, some 200 trials later. His third career was dedicated to developing and disseminating "critical appraisal" strategies for busy clinicians, and ended when he decided he was out of date clinically and returned (at age 49) to a two-year "retreading" residency in General Internal Medicine. His fourth career (and the only one he didn't enjoy) was as Physician-in-Chief at Chedoke-McMaster Hospitals. His fifth career was as Head of the Division of General Internal Medicine for Hamilton and Attending Physician at the Henderson General Hospital. When a chair was created for him at Oxford, he took up his sixth career as foundation Director of the NHS R&D Centre for Evidence-Based Medicine, Consultant on the Medical Service at the John Radcliffe Hospital, and Foundation Co-Editor of Evidence-Based Medicine. At present he is Director of the Trout Research & Education Centre at Irish Lake in Canada, where he reads, researches, writes and teaches about clinical-practice research.