The epidemiological and clinical features of recurrent herpes simplex virus ocular infection (RHSV) were studied. Of 108 patients with primary herpes simplex virus ocular infection (PHSV) who were followed up for two to 15 years 35 (32%) suffered one or more recurrent attacks. The recurrence rate was significantly higher in patients under 20 years of age, but there was no significant difference between recurrence rates in males and females. Of 35 patients with RHSV 17 (49%) had one recurrent attack, 14 (40%) had between two and five, and four (11%) had between six and 15 attacks. The mean time interval between PHSV and the first four RHSV attacks was 10 months, and was shorter in subsequent attacks. The duration and severity of RHSV were reduced in successive recurrences. Patients with more severe conjunctivitis and lid lesions during PHSV ocular infection had a higher incidence of recurrent infection. The severity of the corneal signs in PHSV had no influence on the incidence of recurrent infection. Several clinical forms of RHSV were observed. Conjunctivitis associated with lid lesions was observed in 29 (83%) patients. In six (17%) patients the disease presented as an acute follicular conjunctivitis without characteristic lid or corneal lesions. Dendritic ulcer was found in three (9%) patients, and in one of them it was associated with a disciform keratitis. A chronic blepharoconjunctivitis developed in eight (23%) patients. The epidemiological and clinical features of RHSV were compared with those of PHSV.