Vascular malformations (VMs) are benign lesions of blood vessels originated from an error in vascular morphogenesis during the embryologic phase. Generally, when located in the head and neck region VMs occurs in lips, tongue, buccal mucosa, gums, or palate. The VMs are usually asymptomatic, varies in size and may cause facial asymmetries. Different therapeutic modalities are available to treat VMs, which include surgical excision, cautery, cryotherapy, laser therapy, and sclerosing agents. The authors report 2 patients with extensive VM in the tongue treated with intralesional injection of a low-dose solution of monoethanolamine oleate (MO) and lidocaine. The first patient was a 69-year-old male patient and the 2nd a 65-year-old woman. In both patients, it were performed weekly application of 1:1 MO (Ethamolin) with Lidocaine (lidocaine 3% 1:50,000) in the amount of 0.1 mL of the solution per cm3 of lesion, with a total of 12 applications for each patient at the end of the treatment, with good results and without complications. It is important to be alert in which situation sclerotherapy should be used and that small doses of the sclerotherapeutic agent is essential for the prevention of complications after the procedure. Therefore, these patients showed that the sclerotherapy with MO may be an effective and simple treatment for extensive oral benign vascular lesions. In both patients, there was a great improvement in the clinical aspect of the lesions and patient's satisfaction.