We treated D-54 MG, an extensively characterized human glioma tumor line, in athymic mice with each of 20 antineoplastic drugs and two radiation doses. PCNU, melphalan, cyclophosphamide, and fludarabine were highly active against sc tumors. A single radiation dose of 2500 cGy produced a growth delay (T-C) of 22.0 days and four of seven tumor regressions (TRs), whereas 1500 cGy produced a T-C of 13.2 days and two of 10 TRs. Several other drugs produced smaller T-Cs and fewer TRs. With this model we can make quantitative determinations of the sensitivities of a human glioma line, permitting detailed studies of drug mechanisms.