Sternal osteomyelitis is a potentially lethal complication after cardiac surgery. It may be the cause of postoperative morbidity and mortality. We present a case of deep sternal wound infection after sternotomy. The patient received three treatments of surgical debridement, irrigation, topical negative pressure (TNP) dressing, and hyperbaric oxygen (HBO) therapy. Forty-five HBO therapy sessions were administered. After nine weeks, the sternal wound was healed and completely epithelialized. This conservative therapy can be an alternative and inexpensive method for the difficult sternal wound infection patient.