Two cases of perioperative coronary spasm following ASD closure and OMC are reported. A 36-year-old female had been diagnosed of vasospastic angina and another 47-year-old female patient was diagnosed of effort angina for 99% stenosis of the right ventricular branch preoperatively. Both patients suffered from coronary vasospastic attack and ventricular fibrillation several times within 17 hours postoperatively. Although the coronary dissolution was obtained finally following aggressive cardiac massage, administration of spasmolytic agents, such as NTG, lidocaine, DBcAMP and the start of IABP, the resolution was stormy due to the hemodynamic derangement. To prevent the coronary spastic episode, it is suggested, for patients of possible coronary spasm, to avoid arousal stimulation and to administer spasmolytic agents prophylactically within the first postoperative day.