Objective: Brachial plexus injury is an unusual and under-recognised complication of coronary artery bypass grafting especially when internal mammary artery harvesting takes place. It is believed to be due to sternal retraction resulting in compression of the brachial plexus. Although the majority of cases are transient, there are cases where the injury is permanent and may have severe implications as illustrated in the accompanying case history. We investigated that injury to the brachial plexus was retrospectively assessed in the results of eight patients who underwent median sternotomy for open heart surgery. Methodology: Between March 2006 and October 2008, 455 patients underwent cardiac surgery with median sternotomy. In post operative period peripheric neuropathy symptoms were observed in eight (1.7%) patients. All patients were placed in the hands up position after right internal jugular vein cannulation, and internal mammary artery was prepared for all those patients. The symptoms were classified as pain, sensory impairment and motor impairment. Results: Brachial plexus injury was detected postoperatively in these eight patients. The patients with injured nerves were older and had undergone longer operation times. There were no differences between the patients with injured nerves and the others with respect to mammary artery harvesting or other operative variables. Full recovery occured in seven of eight (87%) patients after six monthes, one (13%) patient suffered from disesthesia. Conclusion: It is known that heart surgery sometimes causes partial brachial plexus injury, especially in the lower trunk. However, these peripheral nerve problems are usually not considered clinically important and are not investigated. Patients undergoing open heart surgery must be closely followed up for peripheral nerve injury during the postoperative period.