Low flow venous malformations in children are a diagnostic and therapeutic challenge. They are present at birth but may not be evident; they have a commensurate growth. They are pure or combined (capillary or lymphatic-venous). At examination, one observed soft, compressible bluish swellings; there is no thrill or bruit. They are slow flow anomalies with venous stasis which may induce thrombosis or localized consumptive coagulopathy. Skeletal distortion or bony hypertrophy or hypoplasia may also be observed; histological examination of surgical specimen reveals infiltration of adjacent structures (skin, bone, muscle); ultrasonography and duplex-Doppler may be helpful in differentiating the venous malformation from lymphatic or arteriovenous anomalies. Diagnosis from hemangioma will be obtained by magnetic resonance imaging; this last investigation will also provide informations on the infiltration of the adjacent tissues by the pathologic process. Standard X ray may show phleboliths of skeletal distortion. Most of venous malformations are asymptomatic and treatment consists in reassuring the child and in giving advice to the parents to prevent trauma to the lesion. Conservative treatment must be advocated (compression garments, prevention of thrombosis with salicylates) since total excision of venous malformation is illusory and postoperative morbidity may be important. Surgical excision of limited cumbersome malformations may be indicated; sclerotherapy of the lesion with Ethibloc makes surgery easier.