Each of blood flow imaging agents has a potential usefulness as an agent for tumor scintigraphy. The usefulness for tumor scintigraphy of two agents, i.e. cerebral blood flow scintigraphy agent 99mTc-HM-PAO and myocardial blood flow scintigraphy agent 99mTc-MIBI, was comparatively studied using rabbits bearing VX-2 cancer. From then to twenty days after the implantation of VX-2 cancer into the femoral region of five rabbits, tumor to soft tissue accumulation ratio (T/S ratio) of each agent was calculated in early images (5 min after injection) and in late images (50 min after injection). Compared with 99mTc-MIBI, the T/S ratio of 99mTc-HM-PAO was higher and, moreover, the washout was delayed. These results suggest that there is a difference in tumor accumulation property between these two agents.