Arteriography was carried out on 54 patients with benign and malignant tumors of soft tissues of the extremities. Results are reported and the most significant angiographic pictures of 28 cases are illustrated in detail. These include 2 neurilemmomas, 1 gigantocellular tumor (sesamoid tumor), 1 synovial gigantocellular tumor, 1 venous racemose hemangioma, 1 capillary-racemose hemangioma, 8 fibrosarcomas, 1 rhabdomyosarcoma, 1 neurosarcoma, 3 synovialsarcomas, 1 malignant mesehnchimoma, 1 mixed epithelioconnectival tumor, 5 ablastic sarcomas, 2 epitheliomas. The arteriographic aspects observed are compared with those described in the literature in order to outline the present knowledge on arteriographic semeiology and diagnosis in benign and malignant tumors of soft tissues. As concerns arteriographic semieology, seven main radiological signs are recognized by the authors, or: 1) displacement of vessels surrounding the growth; 2) dilatation of centripetal and centrifugal vessels; 3) changes in the circulation time; 4) vessels neoformation. Four main angiographic aspects of the newly formed intratumoral vascular network are described; 5) tumor impregnation by the contrast medium; 6) intratumoral blood collections; 7) arterovenous shunts. The frequency and extend of the mentioned radiological features are varying, and different arteriographic pictures may be seen according to tumors type and malignancy. In the majority of benign tumors nearly similar pictures are seen, characterized by absent or scarce vessels of normal appearance. Fibromatous tumors show a homogeneous moderate retention of the contrast medium. Vascular tumors, and particularly some types of angioma, may exhibit rather typical features which consent an angiographic diagnosis of the tumor type. As concerns malignant tumors, rather polymorphic arteriographic pictures are seen in fibrosarcomas, as to tumor vascularization and structural arrangement. Occasionally, vessels are scarce and of normal appearance, and the angiographic pattern resembles that of fibroma; in other cases vessels are more abundant. with irregular caliber and course. The greatest vascular atypia seems to correspond to the histologically most malignant variety of fibrosarcoma. A characteristic common to all observed cases of fibrosarcomas was an evident homogeneous impregnation by the contrast medium. The presence of intratumoral lacune and arterovenous shunts is exceptional. Mention is given of pictures obtained in lipo- and mixosarcomas, sarcomas of muscular origin and angiosarcomas, whereas synovialsarcomas and ablastic sarcomas are more thoroughly considered. Synovialsarcomas are scarcely known in the arteriographic literature. In the three cases observed by the authors, the arteriographic picture resembled that of some types of fibrosarcoma, with abundant and rather atypical vessels, absence of blood lacunae or shunts, regular retention of the contrast medium. These angiographic features, the site, and the roent-genographically visualized skeletal changes ought to consent a radiological diagnosis of the tumor type. In ablastic sarcomas the arteriographic picture is always characterized by a very marked vascular atypia. The frequent occurrence of intratumoral lacunae and arterovenous shunts is suggestive of the high malignancy of these forms. Side effects at the level of limb circulation are also frequently encountered. Tumor impregnation by the contrast medium varies from case to case. To conclude, arteriography is claimed to be able to reveal, in many cases, the presence of a tumor, and to determine its malignancy. The type of the tumor is hardly recognizable, except for some particular cases. Caution is needed in interpreting arteriographic pictures, for the presence of several factors may invalidate the findings. Error causes are analyzed and discussed. Arteriography cannot replace biopsy, but rather complete it as a method of diagnostic ascertainment. Arteriography seems to be clinically indicated: 1) in early diagnosis of cancer of soft tissues of extremities, mainly when the lesion is still scarcely extended or deeply situated; 2) to ascertain tumor extent, to outline its limits towards healthy soft tissues and its anatomical relationships to the bone and vessels. These findings are very significant from a therapeutical, either surgical or radiological, standpoint. 3) to check therapy results. After radiotherapy, arteriography may show a gradual normalization of the angiographic picture of malignancy. In surgically treated cases arteriography may occasionally differentiate between recurrence and cicatricial hardening or granulomatous processes at the operation site. 4) to study tumor vascularization and impregnation; number, site, and course of the supplying vessels. These data are valuable not only for surgical purposes, but also for the application of modern therapeutical methods, such as the introduction of antimitotic or radioactive substances into the afferent circulation.