Moyamoya disease is a rare cerebral vascular disease that results in narrowing of the vessels of the circle of Willis and the formation of a network of collateral vessels at the base of the brain for compensatory perfusion. Moyamoya disease has the highest incidence during the first decade of life, and children present most frequently with transient ischemic attacks. We present two cases of Moyamoya disease in children with associated hypothalamic-pituitary dysfunction. Both children presented to the endocrinologist for decreased growth velocity. One child had hypothyroidism and both had growth hormone deficiency. A review of the literature reveals a few isolated case reports of hypothalamic-pituitary dysfunction occurring with Moyamoya disease and with other states of cerebral vascular insufficiency. We suggest that children with compromise of cerebral vascular perfusion be monitored closely for clinical signs and symptoms of hypothalamic-pituitary dysfunction.