The sonographic features of 23 lymphangiomas (19 pediatric patients) were compared with the pathologic findings. Nineteen lymphangiomas appesred as unicameral (n=2) and multiloculated (n=7) cystic masses. Remaining lesions were inhomogeneously echogenic mass with small cystic portions (n=3) and a mixed pattern (n=1). Fourteen of the multiloculated tumors had thin septa and 6 had solid echogenic foci. The fluid within the majority of the cyst was anechoic in 8 cases and echogenic in 11 cases. Correlation of the sonographic features with the pathologic findings demonstrated that the cystic spaces corresponded to the dilated lymphatic spaces lined with endothelium, separated by septa. Echogenic fluid represented hemorrhage. The echogenic component corres ponded to clusters of very smaller dilated lymphatic channels, thick fibro-fatty septa, or blood clot. The author's experience suggests that the most characteristic sonographic appearance of lymphangioma is a multiloculated cysti mass with thin septa, reflecting the preponderance of fluid-filled spaces. An atypical appearance usually reflects the presence of blood or dominancy of cavernous type. The information obtained with US imaging can help in providing a preoperative diagnosis and in planning surgical resection.