Recently, sirolimus was demonstrated to be effective in treating vascular lesions and lessening the frequency of bleeding and secondary iron deficiency anemia. We present a child with blue rubber bleb nevus syndrome who had prolonged history of iron deficiency anemia secondary to unrecognized gastrointestinal bleeding. Treatment with propranolol, omeprazole and iron had failed. After 2.5 months of sirolimus therapy (trough levels 1 to 5 ng/mL), his hemoglobin concentration improved into the normal range and remained stable. Vascular malformations on both the patient's tongue and in the fundus of his stomach shrank within 5 months of the initiation of sirolimus. In gastrointestinal involvement of blue rubber bleb nevus syndrome sirolimus was found to be effective even in the tongue's vascular lesions.