AIM: To investigate clinical effect of epithelial herpes simplex keratitis (HSK) treated by foscarnet sodium eye drops in the early and middle term.  METHODS:Totally 60 cases (60 eyes) with HSK at Zhongxiang Peoples Hospital from March 2008 to December 2009 were enrolled. All the patients were divided into control group and experimental group randomly. Control group patients were treated by ganciclovir eye drops, 8 times per day, while experimental group patients were treated by foscarnet sodium eye drops, 6 times per day. All patients were treated for 14 days and were followed up for 2 years. The medication outcome and recurrence rate were investigated.  RESULTS:There were no significant differences between control and experimental group in clinical characteristics of patients including age, gender, mean score of symptoms and signs before treatment (P>0.05). After therapy, both the corneal ulcer area and the score of symptoms and signs in control group patients and experimental group patients decreased significantly than those before treatment(P<0.05). But between two groups after treatment, the differences were not remarkable (P >0.05). In the 2 years follow-up, the recurrence rate in experimental group was significantly reduced compared with that in control group (P <0.05). CONCLUSION: Foscarnet sodium eye drops play a similar role in therapy of HSK with ganciclovir eyedrops in early stage, while may decrease the recurrence rate of HSK in the middle term."