['The quality of surgical research, and particularly the reluctance of surgeons to perform randomized controlled trials, has been criticized. The proportion of surgical treatments supported by satisfactory scientific evidence has not been evaluated previously.', 'A 1-month prospective audit was performed of 100 surgical inpatients admitted under two consultants in a general surgical/vascular unit at an urban teaching hospital; the main illness and interventions were agreed through group discussions in each case. The literature concerning the efficacy of each treatment was reviewed, and the evidence was categorized as: (1) supported by randomized controlled trial evidence; (2) sufficient other evidence of efficacy to make a placebo-controlled trial unethical; or (3) neither of the above.', 'Of the 100 patients studied, 95 (95 per cent confidence interval (c.i.) 89-98) received treatment based on satisfactory evidence (categories 1 and 2) and, of these, 24 patients (95 per cent c.i. 17-35) received treatments based on randomized controlled trial evidence and 71 had treatments based on other convincing evidence (95 per cent c.i. 62-80).'] Is surgical practice evidence based?