Wound infection occurred after 14.3 per cent of 433 open heart operations. In 309, saphenous veins were harvested for coronary artery bypass grafting (CABG) and 8.7 per cent of sternal wounds and 12.9 per cent of leg wounds were infected. Only 1.6 per cent of the remaining 124 patients who had open heart operations without leg surgery suffered sternal wound infections. In the CABG group sternal infection was theatre-related and significantly associated with length of pre-operative stay, diabetes and re-operation. Similar organisms were isolated from both leg and sternal wounds which suggest that organisms were transferred from legs to sternum with the veins. No clinically relevant cross infection was demonstrated. Skin disinfection and surgical technique seem more important than antibiotic prophylaxis in the control of these infections.