During regular bacteriological surveillance of cardiac surgical equipment and patients, the Cell Saver apparatus (CSA) was prospectively evaluated to determine if it represented an additional risk for infection. Nineteen patients were studied. After each operation, the effluent from the CSA was sterilely sealed for subsequent culture. A total of 42 aerobic and 42 anaerobic cultures were made. Postoperatively all patients were evaluated daily for four days and before discharge for clinical evidence of infection. Four patients had positive CSA cultures without evidence of postoperative clinical infection. Five patients in whom postoperative infectious complications developed had negative CSA cultures. Ten patients had negative CSA cultures and no evidence of postoperative infection. We conclude that the CSA does not appear to contribute to the risk of infection in cardiac surgical patients and that it is a safe adjunct to cardiac surgery.