High-resolution ultrasonography with small part probes was performed on 20 proliferative vascular lesions of the skin (3 lymphangiomas, 9 hemangiomas, 8 Kaposi sarcomas). All the lesions were submitted to histological examination. The histological cuts were made in the same planes as the ultrasound scans in order to obtain a direct comparison. The sonographic pattern of each histotype is characteristic and correlated with the corresponding histological picture. Lymphangiomas appear as large anechoic communicating cavities; hemangiomas have small hypoechoic areas separated by thin hyperechoic septa. Kaposi sarcomas possess a mixed sonographic structure with ill-defined margins. Ultrasound is proposed as a simple and harmless diagnostic aid to clinical examination of proliferative vascular lesions of the skin.