It was observed experimentally that rise of the mean arterial blood pressure to about mmHg by angiotensin II resulted in a marked increase in blood flow in tumor tissue without increasing blood flow in normal tissue, such as the liver, brain, bone marrow and subcutis. This result clearly indicated the lack of autoregulation of blood flow in tumor tissue. Considering the physiological characteristics of microcirculation in tumor, it is possible to selectively increase tumor blood flow without affecting blood flow in normal tissues. This finding could be applied to cancer chemotherapy for enhancing drug delivery to tumor tissue selectively. Thus, based on these experimental results, clinical studies have been performed in 86 patients with various advanced cancers. Among 72 evaluable patients, there are 8 complete and 26 partial responders with an overall response rate of 47.2%. Nine of 19 patients with gastric cancer responded to the therapy. The clinical procedure and apparatus using in this treatment were described together with technical precaution.