Herpetic infection is a common complication among immune suppressed patients following heart, kidney and bone marrow transplantations,in leukemia patients, in AIDS patients, and during treatment with cytotoxic drugs. In the cases described in the literature, oral acyclovir was recommended as a treatment for the acute infection, as well as for prophylaxis. Intravenous acyclovir is not a routine treatment for herpetic keratitis, but is recommended for cases of insufficient clinical response to oral treatment, and defective absorption of acyclovir by the gastrointestinal tract. We present a patient who underwent 4 liver transplantations,was treated regularly with immunosuppressive drugs, and who developed extensive herpetic keratitits. The keratitis was resistant to both topical ointment and oral acyclovir treatment. Recovery was only achieved following the intravenous administration of acyclovir. We recommend intravenous acyclovir treatment at avery early stage for immune suppressed patients with extensive herpes simplex keratitis.