Recently, several investigators reported the effects of suramin, a drug used in the treatment of trypanosomiasis, onchocerciasis, and an inhibition of the binding of some growth factors to cell surface receptors. In present study, therefore, we examined the effects of epidermal growth factor(EGF) and suramin on cell proliferation and cell cycle kinetics of an established cell line from human lung cancer(PC-13). EGF showed a stimulatory effect on cell proliferation of PC-13, suggesting EGF behaves as a growth factor of PC-13. On the other hand, suramin inhibited the stimulatory effect of EGF to PC-13 in a dose dependent manner. In addition, it was also observed that suramin inhibits the cell cycle progression from G0/G1 phase to S phase. These results indicate that suramin may withhold the cell proliferation and cell growth via suppression of the EGF cell stimulatory effects.