Acute pain after open heart surgery can be moderate or strong and is mostly caused by sternotomy. Pain is the worst during the first two post-operative days and, if not adequately treated, can delay the patient´s recovery from surgery. Sternotomy pain can be alleviated by using paracetamol, non-steroidal anti-inflammatory drugs (NSAIDs) and opioids. All these drugs may have remarkable side-effects which may delay the recovery from surgery: opioids are respiratory depressants and slower the gastrointestinal motility, NSAIDs reduce intrarenal blood flow and may disturb coagulation. Post-operative opioid consumption can be reduced by using wound infiltration analgesia.