Twenty nine published clinical trials with acyclovir (ACV) ophthalmic ointment in the treatment of herpes simplex virus (HSV) corneal disease have been reviewed in which ACV has been demonstrated to be effective in the treatment of simple dendritic ulcers, geographic ulcers, deep corneal HSV infections and ocular disease associated with herpes zoster (VZV) infection affecting the ophthalmic division of the trigeminal nerve. 998 patients were studied. The most commonly occurring adverse reactions were superficial punctate keratopathy (in 9. 8% of patients) and burning or stinging on application of the ointment (4%).ACV ophthalmic ointment was first licensed for the treatment of HSV infections of the eye in September 1981. Spontaneous reports of adverse reactions to ACV ophthalmic ointment to both the UK Committee on Safety of Medicines and the Wellcome Group Adverse Reactions Reporting Centre total 43 cases. These include conjunctivitis, inflammation and pain in the treated eye. In this time it is estimated that there have been approximately one million exposures to the ointment. Thus in general use, tolerance to ACV treatment has been extremely good, and clinical trial data demonstrate that it compares favourably with alternative therapies for HSV corneal disease.