1. Preparation of Materials  VX2 carcinomas were transplanted into the auricles of 50 rabbits. Three days later, rabbits were divided into three groups. Group IA (n=20) was administered anticancer drugs by intraarterial injection over 5 min. Group DIV (n=20) was administered anticancer drugs by drip infusion over 15 min. The two groups were administrated cisplatin (n=10), carboplatin (n=10), docetaxel hydrate (n=10) and adriamycin (n=10), respectively. Untreated VX2 rabbits (n=10) that was administrated sodium saline served as the Control group.  In all groups, tumor microvessels were microangiologically evaluated before administration and 5 min, 15 min and 30 min after administration. Microangiograms of VX2 carcinomas were obtained using a synchrotron radiation system.  2. Microangiographic System  Synchrotron radiation microangiograms were made at the SPring-8 BL20B2 beam line, Hyogo, Japan.  This system consists of a monochromatic X-ray source of 33.3 keV just above the K absorption edge of iodine and an X-ray direct-sensing pickup-tube camera. The system produces an approximately 10 micron­ equivalent pixel size projected onto an input area of field size 10x10 mm.  Non-ionic contrast media of 400 mg iodine/mL was used; 0.8 mL per injection at a speed of 0.2 mL/s, injected into the auricular artery by automated injector. Microangiograms were obtained continually in exposure time 0.2 s at a speed of 5 images/s after contrast material injection. 70-100 images were stored.  3. Image Analysis Image analysis was done with Image-Pro Plus (Media Cybernetics, Georgia, USA).  Among the field where the microvessels with diameters of less than 200 micron­ was observed within the tumor, the field of 2 by 2mm was decided as the Area Of Interest (AOI). The area of the AOI was measured and evaluated changes in tumor microvessels after administration of anticancer drugs quantitatively.  Differences in the AOI between before administration and 30 min after administration of each drugs were evaluated with student's  t test for paired data.