Little is known concerning the natural history of psychiatric morbidity, postoperative delirium, cognitive decline and health-related quality of life (HRQOL) in cardiac surgery patients and the impact of neurocognitive dysfunction on HRQOL after cardiac surgery with cardiopulmonary bypass (CPB). In a prospective study, we followed up for 1 year 30 of the original 34 patients who had undergone cardiac surgery with CPB. Patients were assessed preoperatively, before discharge, and at 1 year after surgery with the Structural Clinical Interview for DSM-IV and a series of neuropsychological tests. Psychometric scales were administered to evaluate cognitive functioning (Syndrom Kurztest), depressive symptomatology (Montgomery-Asberg Depression Rating Scale), posttraumatic stress symptoms (Posttraumatic Stress Syndrome 10-Questions Inventory) and HRQOL (SF-36 Health Status Questionnaire). Delirium Rating Scale (DRS) was used daily over the course of intensive care unit treatment. Postoperative delirium developed in 11 of the 34 patients (mean DRS rating scale score+/-S.D.: 20.36+/-6.22, range: 14-31). Short-term consequences of cardiac surgery included adjustment disorder with depressed features (n=11), posttraumatic stress disorder (n=6), major depression (n=6) and clinically relevant cognitive deficits (n=13). At 12 months, the severity of depression and anxiety disorders improved and returned to the preoperative level, and 6 out of the 30 followed-up patients displayed cognitive deficits. Our patients' HRQOL SF-36 self-reports significantly improved compared with baseline quality of life data. However, 1-year overall lower cognitive function scores were associated with lower HRQOL. Cardiac surgery with CPB is associated with improvements in HRQOL relative to the preoperative period, but the presence of cardiac surgery-related cognitive decline impairing HRQOL is a complication for a subgroup of cardiac surgical patients in the long-term outcome.