Mammary duct ectasia in childhood is a rare disease. It appears typically as a periareolar mammary mass and/or nipple discharge. Even though in the adult age is an acquired disease, its occurrence in children suggests it may constitute a development mammary gland anomaly. Sonography is highly useful in the diagnosis. Differential diagnosis must include other nipple discharge and mammary mass causes as the juvenile fibroadenoma or malignant pathology. This usually is a self-limited process, so that a conservative approach is recommended, even though occasionally surgical treatment is required. We report the case of a 13 years old girl with nipple discharge who finally was diagnosed bilateral mammary duct ectasia.