Subcutaneously and intracerebrally transplanted neurinomas as well as intracerebrally grafted gliomas, both derived from primary tumors with resorptive carcinogens were investigated after injection of micropaque by conventional histologic methods and by postmortem X-ray analysis. Growth pattern and vasculature were similar in subcutaneously and intracerebrally transplanted malignant neurinomas. The most common feature was a parallel arrangement of vessels as shown by microradiography and vessel free zones. In intracerebrally grafted glioma, the growth of tumors was confined to or starting from the ventricular system. Sinusoidal vessels, capillary proliferations and proliferation of vessel wall were found. The outstanding feature was the occurrence of extravascular contrast deposits, thus indicating the vulnerability of tumor vessels and frequency of hemorrhages into these tumors.