The inhibition of herpetic keratitis by a combination of Poly I:C with DEAE-Dextran and IUDR was studied in rabbit eyes. This treatment was administered 72 h after HSV inoculation (daily) for 3 days and continued once daily for another 2-3 days. A significant improvement was detected in rabbit eyes beginning on the first day of treatment, and there was minimal scarring. This improvement in herpetic keratitis coincided with a decrease in the virus titer isolated from rabbit eyes and an increase in interferon titer detected in rabbit tears. The cornea and trigeminal ganglia of treated and control rabbits were tested in order to prove whether this combined treatment could inhibit the migration of HSV from the cornea to the trigeminal ganglia. During the active stage of the disease, HSV was isolated in a lower titer from the cornea of the treated rabbits and from the ganglia of only half of this rabbit group. During the latent stage of the disease, no HSV was isolated from the cornea of either rabbit group, but HSV was isolated from the ganglia explants of the treated rabbits in a somewhat lower titer than from the controls. This treatment administered 3 days after the virus inoculation could not prevent the migration of HSV from the infected cornea towards the trigeminal ganglia.