According to past studies, it is known that, among the compounds of azo dye system, 4-hydroxynaphthalene-1-sulfonic acid derivatives have antiviral activity comparable to the corresponding naphthlonic acid derivatives. Assuming that N-Dodecanoyl-4-hydroxynaphthalene-1-sulfonamide, a type of compounds in which the acetamido group indo N-Dodecanoyl-4-acetamidonaphthalene-1-sulfonamide (PANS-610), an excellent antiviral substance, had been substituted with a hydroxyl, and its hydroxyl derivatives might have a fair degree of antiviral activity, these compounds were prepared and their antiviral activity tested. Contrary to expectations, however, none of these compounds possessed antiviral activity to any extent and this fact suggests that substitution of acetamido group in PANS-610 with hydroxyl is not a good policy.