SummaryWe speculated that asymptomatic patients undergoing routine surgery might be at higher risk of subsequent cardiac events. We studied 183 534 patients with no prior admission for heart disease, aged 50-75 years, admitted electively for one of five operations considered medium to low risk of peri-operative cardiac morbidity, between January 1997 and December 2005. Controls were generated from linked records. Within 3 years 3444 (1.9%) patients undergoing operations had subsequent myocardial infarction ⁄ acute coronary syndrome (MI ⁄ ACS) compared with 3708 (2.0%) controls (p < 0.001). Overall 8406 (4.6%) patients undergoing surgery had MI ⁄ ACS compared with 9306 (5.1%) controls (p < 0.001). Of patients undergoing surgery, 20.2% died compared with 25