Minimally invasive direct coronary artery bypass has the potential to cause an anastomotic failure because of a limited exposure of the operative field and the difficulty of internal thoracic artery harvesting. In the present study, the importance of preoperative marking for an accurate minithoracotomy location and a successful internal thoracic artery harvest was assessed. A paperclip was placed on the left nipple and a chest X-ray was performed in the supine position. By aligning the position of the paperclip to the location of the left anterior descending coronary artery from a coronary arteriogram frontal view, the intercostal space for the minithoracotomy was thus determined. Marking the incisional intercostal space during preoperative left internal thoracic arteriography revealed the number and location of the internal thoracic artery branches at the beginning of the harvest. This preoperative marking technique allowed for a more adequate exposure of the operative field and an easier internal thoracic artery harvest which therefore contributed to an improvement in the operative results.