Bacillus Calmette-Guerin cell-wall preparation was injected along with avian sarcoma virus in the brains of newborn Fischer 344 rats, and subsequent glioma induction was compared with rats injected with avian sarcoma virus alone. The percentage of glioma induction and survival were found to be directly related to avian sarcoma virus concentration (10(0), 10(-1), 10(-2), and 10(-3)). A significant reduction in glioma induction occurred when BCG cell-wall preparation was injected with 10(-2) ASV concentration. Above that concentration of ASV, the tumor induction was not significantly affected by bacillus Calmette-Guerin cell-wall preparation; below that concentration, the tumor induction was too low with avian sarcoma virus alone to evaluate an effect.