In CDDP hepato-arterial injection therapy, platinum (Pt) concentration in hepatic and peripheral venous blood were determined in two groups with different injection rates, and the blood kinetics of Pt was examined. Seven cases of digestive cancers having liver metastases were given CDDP (100 mg) selectively into the proper hepatic artery at a constant rate (10 or 40 min). After injection, concentration of non-protein-bound Pt in hepatic and peripheral venous blood were determined. Pt concentration and AUC value were higher in hepatic venous blood at injection rate than peripheral venous blood. On the other hand, Pt concentration in hepatic venous blood in the cases 10 min-injection were higher than those received 40 min-injection, but neither Pt concentration in peripheral venous blood nor incidences of the side effects and abnormal clinical findings were influenced by the injected rates.