To utilize the high lympholytic effect of corticosteroids with minimal systemic adverse effects, we used intraarterial corticosteroid infusion in the treatment of 8 patients with primary central nervous system lymphoma (PCNSL). One patient had recurrent PCNSL, while the other patients had primary disease. Following standard radiotherapy with or without some systemic or intrathecal chemotherapy, prednisolone (60-100 mg in total) or dexamethazone (12 mg in total) was rapidly infused through the carotid arteries in all patients and also through the left vertebral artery in 5 patients. No acute or late complications of this treatment were observed. All 8 patients achieved complete or partial response. Four patients died of the disease, while the other 4 were alive with (1 patient) or without (3 patients) disease at 8-37 months after treatment, giving a 2-year survival rate of 55%. Intraarterial administration of high-dose corticosteroids appears to be a feasible treatment modality. This method may be used in preradiotherapy setting to evaluate response of PCNSL in future studies.