It was shown that human interferon alphaII modulates sodium current in human neuroblastoma cells by changing the kinetic parameters of fast sodium current. The maximum effect was observed 5-10 min after interferon application. The action of 2'-5'-oligoadenylate on sodium current is identical to that of interferon alphaII. The effect of 2'-5'-oligoadenylate is enhanced as its concentration in pipette solution rises. The same effect of 2'-5'-oligoadenylate was demonstrated in mouse neuroblastoma N1E-115 cells.