The anti-herpes simplex virus (HSV) effect and cytotoxicity of a new nucleoside analogue, 9-(1,3-dihydroxy-2-propoxymethyl)guanine(DHPG) in rabbit cornea were studied. In tests of the anti-HSV effect of DHPG, even 0.03% ointment, given 5 times per day for 2 days, prevented lesion formation. The preventive effect of DHPG was much stronger than that of acyclovir(ACV) or 5-iodo-2′-deoxyuridine(IDU). In tests on the therapeutic effect of DHPG against dendritic ulcers, 0.3% ointment, given 5 times per day for 4 days, had a dramatic therapeutic effect. The effect was stronger than that of 3% ACV or 0.5% IDU ointment. Application of 0.3%, 1% or 3% DHPG ointment to normal rabbit corneas, 5 times per day for 2 weeks resulted in no histopathological abnormalities. The above results show that DHPG is superior to ACV or IDU for treatment of HSV infections.