Abstract: A method of treating tumors that express a receptor for IL-13 is disclosed. The method involves directly introducing into the tumor a cytotoxin that targets the IL-13 receptor. The cytotoxic agent can be introduced by convection-enhanced delivery through a suitable catheter or by other means. Where a convection-enhanced catheter is employed, the method involves positioning the tip of a catheter at least in close proximity to the tumor. After the catheter is positioned, it is connected to a pump which delivers the active agent through the catheter tip to the tumor. A pressure gradient from the tip of the catheter is maintained during infusion.