OBJECTIVE Open chest (OC) and subsequent delayed sternal closure (DSC) has been described as a useful method in the treatment of the severely impaired heart after cardiac surgery. METHODS Prolonged open chest was used in 142 to 3373 adult cardiac operations (4.2%) between January 1987 and December 1993. The indications were: hemodynamic compromise (121), intractable bleeding (9) and arrhythmias (12). Delayed sternal closure was carried out in 123 of 142 patients at a mean of 2.0 +/- 1.4 days (range 0.5-8 days). Open chest and DSC were used proportionally more frequently after combined cardiac surgery (28/293, 9.6%) than after coronary artery bypass grafting (CABG) alone (108/2891, 3.7%) or valve operation (6/230, 2.6%). RESULTS Ninety-seven of the 123 who had DSC (78.9%) survived and were discharged an average of 8.6 +/- 4.2 days after closure. Fourty-five patients died: 19 before DSC and 26 after this method. Mortality was related to indications for OC: when the indication was low cardiac output the mortality was 38.6%, for hemodynamic collapse on closure 0%, diffuse bleeding 33.3% and arrhythmias 27.3%. Delayed sternal closure in patients without intraaortic balloon pump support was more likely to be successful (mortality rate 4/25, 16.0% versus 35/76, 46.3%, P < 0.01). Superficial sternal wound infection occurred in 2 of 123 (1.6%) patients after DSC, mediastinitis in 1 (0.8%) and sternal dehiscence in 3 (2.4%) patients, which does not differ from a control population that had primary sternal closure. The follow-up of 97 survivors at an average of 28 +/- 4 months revealed an improvement of NYHA class by 1.4 +/- 0.4. There were 16 deaths (13 cardia-related) during the follow-up period and 3 redo CABG. One case of sternal osteomyelitis occurred without any other late sternal morbidity. CONCLUSIONS This study shows that OC with DSC is a beneficial adjunct in the treatment of postoperatively impaired cardiac function, profuse hemorrhage and persistent arrhythmias. It can be performed without increased sternal morbidity. Long-term results are also encouraging.