Treatment of brain cancer is limited in part by inefficient intracellular delivery of drugs and DNA for chemotherapy and gene therapy, respectively. This study tested the hypothesis that ultrasound may be used to enhance intracellular delivery and efficacy of chemotherapeutics and genes in glioma cells in vitro. First, suitable ultrasound conditions were identified by measuring intracellular uptake of calcein and viability of GS 9L rat gliosarcoma cells after a range of different ultrasound exposures. We selected sonication at 10 J/cm2, which achieved intracellular delivery of approximately 10(6) molecules/cell. Next, glial cells were sonicated with varying concentrations of model chemotherapeutics: BCNU and bleomycin. For both drugs, cytotoxicity was increased in a synergistic manner when accompanied by ultrasound exposure. Finally, expression of a plasmid DNA encoding a GFP reporter was increased up to 30-fold when exposed to ultrasound. Altogether, these findings suggest that ultrasound may be useful to increase the efficacy of chemotherapy and gene therapy of glioma cells.