Venous malformations (VMs) are congenital disorders that constitute about 40% of all vascular anomalies. These lesions do not regress spontaneously and may increase in size during childhood. The case of a 10-year-old girl with an extensive oral VM is reported. Intraoral examination revealed the presence of purplish nodules in the alveolar mucosa and gingiva from anterior maxilla. Doppler ultrasound showed a well-defined hypoechoic image and increased vascularization with low blood flow for the alveolar mucosa lesion. The patient was submitted to intralesional injections of the ethanolamine oleate/mepivacaine sclerosing solution. After four sessions, there was a significant reduction of the lesions. However, the patient abandoned the treatment and the oral VM grew progressively. After 1 year, sclerotherapy was resumed and performed weekly. After 10 session of sclerotherapy, the oral VM totally regressed. The childhood is a critical period for oral VM growth. Doppler ultrasound and sclerotherapy can be effective for the management of extensive lesions in children.