Intratumoral infusion of a recombinant targeted toxin (NBI-3001) consisting of the receptor binding domain of human interleukin 4 (IL-4) and Pseudomonas aeruginosa exotoxin A is an investigational treatment for malignant brain tumors. This 27-year-old male patient presented with a recurrent malignant glioma WHO grade IV after surgery and adjuvant radiation and chemotherapy. The recurrence was treated with intratumoral infusion of NBI-3001 at a dose of 9 microg/ml in 66 ml of infusate. Treatment resulted in long-term survival for 3 years after toxin infusion with a durable tumor response. There were some permanent neurological side effects resulting from toxin infusion. The patient eventually died after a late local recurrence of the known brain tumor. Such clinical evolution of a malignant glioma after a single round of immunotoxin infusion is rather unusual. The late local recurrence may suggest that repeated courses rather than a single infusion of intratumoral toxin are possibly needed for successful long-term tumor control.