In arterio-venous malformations, arterial trans-catheter embolization can be considered as a definitive treatment, a pre-operative devascularizing technique, and a palliative treatment of those not surgically operable malformations. A very important point is choosing the correct way where to introduce the catheter and the embolizing devices. The most known devices are: synthetic fibrin foam (Gelfoam, Spongostan), Gianturco coils, and among the non reabsorbable devices a polyvinylic alcohol foam (Ivalon), the isobutyl-2-cyanoacrylate and silicone. Furthermore detachable balloons and bristle-brushes can be used. Many parameters must be taken into consideration: hemodynamic fluxes of the lesion, type of vascularization, extension of the lesion, aim of the embolization, possible risks. When embolizing large territories, the protocol must foresee several performances for the control of the embolized vessels, the presence of collateral circulation, the extension of the embolization and other afferent arteries to the lesion. Regarding the permanent occlusions it is preferable to utilize fragments of Ivalon, small silicone spheres or liquid silicone; finally, reabsorbable device must be used in the distal embolizations and non reabsorptible in the proximal embolizations. The best results have been achieved in the traumatic lesions where a direct communication exists between an artery and a vein. Among the arterio-venous malformations the best results have been achieved in cranio-facial angiomas with low flux. The possible complications are consequences of ischemia: necrotic musculo-cutaneous, cerebral or troncular changes.