To derive and compare the need for hospitalization during 2 years prior to coronary artery bypass grafting (CABG) and 2 years after, all the patients from western Sweden in whom CABG without simultaneous valve surgery was performed between June 1988 and June 1991 were evaluated. Hospitalization prior to and after surgery was derived via questionnaires sent to the patients and via data from their hospital medical record forms. In all, 2099 patients were studied. The mean total number of days in hospital was 16 during the 2 years before and 24 including surgery and postoperative complications during the 2 years after the operation (p < 0.001). When the days for operation and postoperative complications were excluded, the mean number of days after operation was 7 (p < 0.001). Hospitalization due to myocardial infarction, angina pectoris, percutaneous transluminal coronary angioplasty and other investigations for heart disease were significantly reduced after CABG. On the other hand, hospitalization due to chest pain with causes other than ischemic heart disease, congestive heart failure, arrhythmias, and reoperation was more frequent during the 2 years after surgery. The total number of days in hospital was higher during the 2 years after CABG than during the 2 years before, despite the fact that hospitalization due to ischemic events was significantly reduced after the operation.