Various conservative and surgical procedures are available for the management of aggressive hemangiomas in infancy and childhood. One of them is magnesium seeding, a treatment modality developed more than 90 years ago but neglected for a long time. The technique consists of implanting 0.5- to 1-mm-thick wires of 99.8% pure magnesium into the tumor mass. During repeated courses oxidation of the metal results in fibrosis and cicatricial transformation of the tumor. Indications, technique and results are discussed.