Diffuse neonatal hemangiomatosis (DNH) is a rare, frequently fatal disorder characterized by multiple cutaneous and visceral hemangiomas. Complications include high-output cardiac failure, hemorrhage, hepatic failure, and consumption coagulopathy. We present two cases of neonates with DNH. We prescribed cyclophosphamide after failure of corticosteroids. Cyclophosphamide induced a fast regression of the lesions with no side effects in both infants. We were able to stop treatment after 3–4 courses of cyclophosphamide in both infants because of the excellent response. Cyclophosphamide seems to be a safe and effective treatment in patients suffering from life-threatening DNH unresponsive to corticosteroids. Pediatr Blood Cancer 2006;46:239–242. © 2005 Wiley-Liss, Inc.