Moyamoya disease is a rare cerebrovascular occlusive disease. We aimed to present two cases of Moyamoya diagnosed patients undergoing general anaesthesia and emphasize important issues about the anaesthetic management of these patients. 28 year old male patient was admitted to the hospital with complaints of weakness in his left arm and leg. Preoperative examination revealed quadriparesia and disturbed consciousness and angiography revealed occlusion in internal carotid arteries bilaterally. Encephaloduroarteriocineangiosis operation was planned. The patient was observed with meticulous noninvasive monitorization. During induction of anesthesia atropine, fentanyl, thiopentone and vecuronium bromide were administered. Anaesthesia was maintained by sevoflurane in oxygen (O2) nitrous oxide (N2O) mixture. End tidal carbondioxide (ETCO2) level was kept between 35-40 mmHg. There was no complication during peroperative and postoperative period. 4.5 year old male child was hospitalized in order to investigate his growth retardation. During his follow up, MRI angiography revealed serious narrowing in cavernous segments of internal carotid arteries bilaterally. Encephaloduroarteriocineangiosis operation was planned. After meticulous noninvasive monitori-zation, induction of anaesthesia was achieved O2+N2O and no complication was observed during the peroperative and postoperative period. During anaesthetic management of these patients, it is crucial to avoid hypocapnia due to hyperventilation and steal phenomenon secondary to hypercapnia. Otherwise ischemia in frontoparietal region which is predominantly involved by Moyamoya disease may adversely affect the prognosis
