Between January 1981 and December 1991, 4137 adult patients underwent various cardiac procedures via a median sternotomy under cardiopulmonary bypass. The overall infection rate was 1.33%, including superficial wound infections (SWI) (1.18%) and deep sternal infection (DSI) (0.145%). Pericardial and retrosternal suction drains with a vent allowed a better drainage of blood and serosities and probably contributed to our low DSI rate. Eleven factors predisposing to infection were evaluated by Fisher's exact test. Only the operative urgency (P = 0.006), reexploration for bleeding (P = 0.00001) and preoperative renal failure (P = 0.0005) were statistically significant. Twenty of our infected patients had no risk factors for infection. When the risk factors described in the literature were applied to our infected patients, only one had no risk factor.