Background: Venous malformations (VM) of lower extremities have characteristic symptoms, especially swelling, pain at rest or with dependence, or in the morning, or with exertion. Sclerotherapy has been applied and has been showed to alleviate the associated signs and symptoms. The aim of this study is to evaluate the outcomes of ethanol sclerotherapy for VM of lower extremities. Methods: The 21 patients of intramuscular VM of the lower extremities, who received percutaneous sclerotherapy using absolute ethanol in our institute, were reviewed retrospectively. The average age at the time of the initial diagnosis was 18.6 years, and average follow-up period after last sclerotherapy is 19.4 ± 13.5 months. The postinterventional changes of the associated signs and symptoms were evaluated by utilizing original VM scoring system. Results: The average number of sclerotherapy sessions was 2.6 times per case. The average total amount of ethanol used in each patient was 41.3 ml. Sclerotherapy reduced the associated signs and symptoms in many of the patients (n = 19/21). Preinterventional VM score as the overall baseline status was 10, and the average VM score after sclerotherapy was 4.1. There was no inverse correlation between the amount of ethanol used and the VM score. In seven cases treated more than three times, reverse correlation between the "VM score" and the number of sclerotherapy sessions was demonstrated (p &lt
0.05, ρ = 0.8214). Conclusions: The characteristic symptoms and signs of the VM were improved by sclerotherapy. More than three sessions of ethanol sclerotherapy improved the overall status of extensive intramuscular VM in lower extremities. Level of Evidence: Level IV, therapeutic study. © 2012 Springer-Verlag.