To the Editor.— An excellent review of the treatment of superior vena cava syndrome (SVCS) by Drs Lokich and Goodman (231:58, 1975) mentioned that chemotherapy is effective in treating SVCS resulting from acute lymphocytic leukemia (ALL) and non-Hodgkin lymphoma (NHL), but the authors did not refer to the drug combination best used. Therefore, we would like to report briefly two cases treated with a combination of chemotherapeutic agents—prednisolone and vincristine—that are known to cause rapid lysis of tumor cells, with the potential risk of uric acid nephropathy. Report of Cases.—Case 1.— A 13-year-old girl was seen at Oklahoma Children's Memorial Hospital with a three-week history of progressive pain in the right shoulder, shortness of breath, cervical adenopathy, and facial edema. Substantial enlargement of the mediastinum was noted on the chest x-ray film. Non-Hodgkin lymphoma was diagnosed by a mediastinal biopsy. Preventive measures were initiated against hyperuricemia. Substantial reduction