Infantile hemangiomas (IHs) are common benign tumors of childhood. IHs often regress satisfactorily without intervention, but a subset of IHs may lead to functional or cosmetic morbidity necessitating therapy. PHACE syndrome is characterized by a variety of neurocutaneous and vascular anomalies that typically include segmental hemangiomas. We present an infant with PHACE syndrome and segmental IH that failed conventional first-line therapies. Treatment with sirolimus provided benefit with regression of the cutaneous IH. As an inhibitor of the mammalian target of rapamycin (mTOR) pathway, the effective use of sirolimus may shed light on the emerging role of mTOR signaling in the development and pathogenesis of IHs.