Lymphatic malformation (LM) is a localized and rare benign anomaly of the lymphatic system. Surgery is the primary form of treatment, but total resection is difficult and generally not possible. The least invasive and most effective form of treatment is injection sclerotherapy with sclerosing agents. Here, we report a case of LM in a baby, detected at prenatal ultrasound. The aim of this report is to assess the importance of ultrasonography in the prenatal diagnosis, therapy and follow-up of LM's.