To assess the incidence and clinical characteristics of herpes simplex keratitis in France. National multicenter prospective study on herpetic keratitis. During a 3-month study period (September-December 2002), all cases of herpes simplex keratitis were prospectively reported by a randomly selected sample of 412 ophthalmologists representative of the 5471 French ophthalmologists in terms of gender, geographic distribution, and clinical practice. The following set of assumptions were made to calculate the incidence of herpectic keratitis: (1) the participating (self-selected) ophthalmologists in the study could adequately represent French ophthalmologists, (2) estimates based on the 3-month study period could be used to calculate the annual incidence (i.e., no significant seasonal variations), and (3) all patients suffering from herpetic corneal lesions consult or are referred to an ophthalmologist. We calculated the incidence of herpetic keratitis by (1) estimating the average number of incident cases per ophthalmologist per year, (2) multiplying the average number of incident cases by the total number of French ophthalmologists (n = 5471), and (3) dividing the result by the French population. Four hundred twelve ophthalmologists reported 357 cases of herpes keratitis. We estimated that the overall incidence of herpetic keratitis during the study period was 31.5 per 100,000 person-years (95% confidence interval [CI], 25.5-37.5), and incidences were 13.2 per 100,000 person-years for new cases (95% CI, 10.4-15.9) and 18.3 per 100,000 person-years for recurrences (95% CI, 14.6-22.1). The most frequent types were dendritic keratitis (56.3%, n = 153), stromal keratitis (29.5%, n = 81), and geographic keratitis (9.8%, n = 27). Other ocular lesions were associated with keratitis in 35.0% (n = 125) of cases; the most frequent were conjunctivitis (18.8%, n = 67), uveitis (11.8%, n = 42), and/or lid involvement (8.6%, n = 31). This prospective epidemiological study provides an estimate of the incidence of herpes keratitis in France. Herpetic keratitis remains an epidemiologically important eye disease that justifies the need to pursue health care and research programs aimed at improving the outcome of ocular herpetic disease.