The stilbenes 4,4′-diaminostilbene-2,2′-disulfonic acid, 4-aminostilbene disulfonic acid, and dinitrostilbene-2,2′-disulfonic acid were tested as enhancers for the gypsy moth, Lymantria dispar (L.), nucleopolyhedrovirus (LdNPV). 4-Amino nitrostilbene disulfonic acid had no effect on the activity (LC50) of LdNPV, whereas both 4,4′-diaminostilbene-2,2′-disulfonic acid and 4-aminostilbene disulfonic acid were inhibitory. Diethylstilbestrol, a stilbene synthetic estrogen, and two synthetic estrogens (i.e., estradiol-17-acetate, estrone acetate) had no effects on viral activity. Two stilbene dyes (i.e., direct yellow 62, brilliant yellow 6) and a stilbene optical brightener (i.e., Tinopal LPW) significantly increased the activity of LdNPV. Activity was increased by approximately 230-fold by Tinopal LPW, 26-fold by direct yellow 62, and 36-fold by brilliant yellow 6. This study demonstrates that some stilbenes can act as enhancers, whereas others do not.