Stimulatory effects of epidermal growth factor (EGF) and transforming growth factor-α (TGF-α) on the growth of squamous cancer cell lines established from human oral cancer tissue with moderate differentiation were studied in vitro. After culturing in serum-free media for 24 hours, growth factors-EGF only, TGF-α only and EGF, TGF-α together-were added to the media and numbers of cells were analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and compared with the control at 96, 144 hours. Each of EGF and TGF-α showed statistically significant stimulatory effects on the growth of cells respectively. Dose-dependent relationship of the stimulatory effects were not clearly demonstrated. The effects of EGF were higher than those of TGF-α and combinative administration showed higher effects than those of single uses. In conclusion, EGF may play an important and major role in differentiation and growth of human oral squamous cancer cells. TGF-α, produced from cells activated by EGF, also can stimulate the cell growth and could be an alternative ligand for EGF receptor.