Moyamoya disease is a rare disorder of cerebrovascular circulation. A review of the literature failed to reveal the association of heterotopic ossification in patients with this disease; such a case is now presented. The patient described had atraumatic intracranial hemorrhage, was in a coma for a period of time, underwent ventriculostomy and shunt placement, and was left with residual spastic hemiparesis. Evidence of heterotopic ossification around the hemiparetic shoulder and hip was subsequently noted on radiographic studies and was managed conservatively. Heterotopic ossification may be a rare complication of the neurological deficits associated with moyamoya disease and needs careful consideration when joint stiffness persists, despite usual conservative measures.