Herpes simplex disciform keratitis is a difficult condition. The general feeling is that it is an immune disease, mediated by the virus, possibly located in the endothelial cells. It is frequently combined with inflammation in the trabecular meshwork and with uveitis. There is some controversy in relation to treatment and it has been suggested that anti-vitals will control herpetic disciform keratitis, particularly if the patient has never had steroids previously. The authors of this paper have, in the past, published data which showed that Acyclovir, with corticosteroid, was necessary in the management of disciform keratitis. The data suggested that Acyclovir on its own was not effective. It remained to be answered whether Acyclovir on its own would be effective in patients who never had steroids for any reason previously. This paper demonstrates clearly that it is necessary, irrespective of whether patients have had steroids in the past or not, to combine corticosteroids with Acyclovir in the management of herpetic disciform keratitis. Acyclovir, on its own, is shown to be ineffective. It has also been suggested that Acyclovir is non-toxic. In a general way this is true, but the authors suggest that Acyclovir ointment does produce a punctate keratitis in patients with tear film disease, and that oral Acyclovir is preferable in such patients.