Suramin,a drug used for the treatment of African trypanosomi-asis and onchoceriasis,has potential anti-cancer activity.In the present study.the effect of suramin on proliferation of human head and neck squamous cellcarcinoma cells was determined.A significant growth inhibition in all threecell lines tested was observed when the concentration of suramin was 100μg/ml or more.The hypothesis was tested whether growth inhibition may bedue to selective interference with the action of epidermal growth factor.Suraminat growth inhibiting concentrations only partly antagonized the growth slimulat-ing effect of EGF at concentrations as low as 0.1 ng/ml,indicating that alsoother mechanisms of action may contribute to the growth inhibitory activity ofsuramin.Furthermore,evidence was found that also serum proteins other thangrowth factors presented in the culture medium have a growth stimulating effecton cells and a strongly antagonistical effect on suramin activity. Suramin,a drug used for the treatment of African trypanosomi-asis and onchoceriasis,has potential anti-cancer activity.In the present study.the effect of suramin on proliferation of human head and neck squamous cellcarcinoma cells was determined.A significant growth inhibition in All threecell lines tested was observed when the concentration of suramin was 100μg/ml or more.The hypothesis was tested meaning that may bedue to selective interference with the action of epidermal growth factor.Suraminat growth inhibiting concentrations only partly antagonized the growth slimulat-ing Effect of EGF at concentrations as low as 0.1 ng/ml, indicating that alsoother mechanisms of action may contribute to the growth inhibitory activity ofsuramin.Furthermore,evidence was found that also serum proteins other thangrowth factors presented in the culture medium have a growth stimulating effecton Cells and a polar antagonistical effect on suramin activity.