We report a useful method for the establishment of cell lines in vitro from human tumors. One of the obstacles to establishing pure human cancer cells in vitro is contaminating fibroblasts in cultures. This obstacle could be overcome by selective-growth control of fibroblasts treated with serum-free GIT medium and their selective elimination with antibiotic Geneticin (G418-sulfate). In this study, the process of establishing cultured cell lines from two oral cavity cancers is demonstrated using GIT medium and Geneticin. The comparative study of the growth of cells of the two oral cavity cancers and of two control normal fibroblast cell lines supported the selective growth inhibition and elimination of normal fibroblasts by the "G-G method".