BACKGROUND: Postoperative pain may be severe after open heart surgery (OHS). High thoracic epidural analgesia may reduce postoperative pain and improve the pulmonary function. We investigated the effect of epidural analgesia after median sternotomy METHODS: Fifty-six patients were randomized to epidural patient controlled analgesia (PCA) or conventional analgesia (control). Patients received OHS with standardized general anesthetic technique. The day before surgery, patients allocated to the PCA group had an epidural catheter inserted at level T4-5. Proper placement was tested with small dose of lidocaine and epinephrine. Epidural catheter was removed 3 days after surgery. Patients in control group received conventional nurse controlled analgesia. Postoperative assessment included daily visual analog scoring (VAS) and pulmonary function test 3 days after surgery. Complication and patients satisfaction were also evaluated. RESULTS: The VAS scores did not significantly differ between the groups, except 12 hours after surgery during coughing. Patients with PCA awoke and were extubated significantly earlier than patients in control group. Significantly higher forced expiratory volume in 1s and peak expiratory flow rate were seen in PCA group than in control group. No significant thoracic epidural related complications occurred. CONCLUSIONS: Thoracic epidural PCA provided better analgesia and allowed earlier extubation. Thoracic epidural PCA yields a slight, but significant, improvement in pulmonary function.