Epidermal growth factor receptor (EGFR) plays an important role in the progression of malignancy in gliomas. We studied the growth inhibition of the malignant glioma cell lines using an antisense EGFR oligodeoxynucleotide enveloped with Lipofectin. At a concentration of 5 microM of the antisense EGFR oligodeoxynucleotide enveloped with Lipofectin, the proliferation of three malignant glioma cell lines was significantly inhibited (p < 0.05) compared with that of the cells exposed to 5 microM sense EGFR oligodeoxynucleotide. The activity of the tyrosine kinase and the DNA synthesis was also significantly suppressed (p < 0.05). These findings show that the antisense EGFR oligodeoxynucleotide enveloped with Lipofectin has a possibility to become a useful gene therapy against malignant gliomas.