BACKGROUND: To report seven cases diagnosed as cytomegalovirus endotheliitis and treated with topical 2% ganciclovir following penetrating keratoplasty. DESIGN: A retrospectively comparative case series. PARTICIPANTS: A retrospective interventional case series, including seven eyes of seven patients with cytomegalovirus endotheliitis after penetrating keratoplasty. METHODS: Clinical and immunological characteristics were studied in seven penetrating keratoplasty cases with positive quantitative polymerase chain reaction results for cytomegalovirus DNA from aqueous taps and treated with topical 2% ganciclovir. MAIN OUTCOME MEASURES: Clinical features and responses to topical 2% ganciclovir. RESULTS: Seven immunocompetent patients experienced acute anterior inflammation with graft oedema and pigmented keratic precipitates after penetrating keratoplasty. Their immunological profiles showed immunoglobulin G cytomegalovirus (+) and immunoglobulin M cytomegalovirus (-) in all cases. Topical 2% ganciclovir was prescribed every 2 to 3 h daily as induction therapy and every 4 h as long-term maintenance therapy. All cases had undetectable cytomegalovirus DNA after follow-up aqueous taps. Topical 2% ganciclovir preserved endothelium of cytomegalovirus-infected grafts at early stage and also provided a steady anticytomegalovirus environment for further regrafting in failed grafts at late stage. Acute inflammation reactivated in two cases and was suppressible by steroid under topical ganciclovir. No delayed re-epithelialization and any toxicity were observed. To date, no case treated in this way had displayed cytomegalovirus recurrence. CONCLUSIONS: Continuous topical 2% ganciclovir and a topical steroid adjusted by anterior inflammation are suggested after penetrating keratoplasty in all cases with cytomegalovirus endotheliitis to prevent cytomegalovirus recurrence.