Introduction: Kaposiform Hemangioendothelioma (KHE) is a rare vascular tumor, which is associated with the severe coagulopathy known as Kasabach-Merritt phenomenon (KMP). This condition has a mortality rate around 20%. Many treatments have been described, but despite the potentially severe complications that these patients may present, so far there is not a single protocol to follow. International experimental models have used Sirolimus (SRL), a macrolide mTOR inhibitor with antiangiogenic effect. However, its use in children against vascular anomalies, such as KHE, is limited. Objective: To report the development of two patients with KHE and KMP treated with SRL in cancer centers, after multiple failures with other therapies. Case reports: Two infants with severe KHE associated to FKM, resistant to standard therapies and who overcame life-threatening complications after treatment with SRL are presented. After SRL, the two patients showed normal platelet counts and coagulation tests, reduced lesion size and associated pain, no presence of life threatening conditions or side effects. Conclusion: SRL appears to be effective and safe in treating KHE, representing a new available therapeutic option.