The potential disadvantage of using the radial artery for coronary artery bypass grafting is its increased tendency to vasospasm. Therefore, different antispastic agents are being used in the perioperative and postoperative period. During the preparation of the radial artery, normal local and systemic temperatures are lost.We investigated the effects of topical normal saline solution at 20 degrees C (group SI), normal saline solution at 36 degrees C (group SII), diltiazem at 20 degrees C (group DI), and diltiazem at 36 degrees C (group DII) on radial artery free flow. Each group contained 10 patients undergoing coronary bypass surgery. Free flow and local temperature were measured at 3 stages: after the exploration and preparation of the distal 3 cm of the radial artery, after total preparation of the radial artery, and a median of 12 minutes after the pedicle had been sprayed with one of the agents.Parallel to the significant decrease of the second local temperatures (P < .001), the second flow of the 4 groups decreased significantly (P < .001).Hypothermia plays an important role in radial artery vasospasm, and normothermia may be the best perioperative vasodilating agent since the normal radial artery flows were reached with normothermia.