Objective To describe mortality and morbidity during a period of 2 years after coronary artery bypass grafting in relation to gender. Design Prospective follow-up study. Setting Two regional cardiothoracic centres which performed all the coronary artery bypass operations in western Sweden at the time. Sub|ects A total of 2129 (1727 (81%) men and 402 (19%) women) consecutive patients undergoing coronary artery bypass surgery between June 1988 and June 1991 without concomitant procedures. Results Females were older and more frequently had a history of hypertension, diabetes mellitus, congestive heart failure, renal dysfunction and obesity. In a multivariate analysis, taking account of age, history of cardiovascular diseases and renal dysfunction, female sex appeared as a significant independent predictor of mortality during the 30 days after coronary artery bypass grafting (/><0-05), but not thereafter. Various postoperative complications including neurological deficit, hydro- and pneumo-thorax, perioperative myocardial damage and the need for assist devices and prolonged reperfusion were more common in females than males. Conclusion Females run an increased risk of early death and the development of postoperative complications after coronary artery bypass surgery as compared with males. Late mortality does not appear to be influenced by gender and the long-term benefit of the coronary artery bypass graft operation is similar in men and women.