Over a 5-year period from 1985 to 1989, 2760 patients underwent open heart surgery at the University Hospital of Wales. Of these, 44 (1.6%, 35 men, mean age 61 years) developed median sternotomy dehiscence 2-40 (median 9) days after surgery. Infection was an associated factor in 18 patients (41%) and Staphylococcus aureus the predominant isolate in seven of those. Thirty-seven patients underwent rewiring of the sternotomy wound and seven patients underwent debridement, removal of wires and delayed closure. In those undergoing rewiring, sternal stability was maintained in 34 patients (92%). There were seven deaths (16%), of which two were considered to be wound-related. Median hospital stay of survivors was 34 (range 16-84) days. Comparison with 88 matched controls by univariate analysis showed preoperative chronic obstructive airways disease, reduced FEV1/FVC ratio (both P < 0.001) and smoking (P < 0.05) were all more common in the dehiscence group. In addition, reoperation for bleeding (P < 0.05), prolonged bypass time, postoperative ventilation period and length of stay in the intensive care unit (all P < 0.001) were more common in the study group.