Pharmacokinetics and antitumor activity of MX2.HCl (MX2), a new morpholino anthracycline, were investigated in rats transplanted 9L gliosarcoma cells in the brain. (1) Pharmacokinetics: AUC of MX2 in the brain tumors which received intracarotid and intravenous injection of 2mg/kg of MX2 were 117.50 and 55.94 micrograms.hr/g, respectively. AUC of the brain tissue was 1.38-3.90 micrograms.hr/g. (2) Antitumor activity: The inhibition of cell growth at the concentration of 0.1 micrograms/ml was 73.1% with MTT assay. The mean survival time in tumor-bearing rats after intracarotid and intravenous injection of 2mg/kg of MX2 prolonged significantly. Therefore, it seems that MX2 will become an efficacious drug for the treatment of malignant glioma.