The purpose of this study was to review and analyze the records of herpes simplex infections from a specialist Oral Medicine clinic in Iceland, to investigate the clinical impression that the age of patients experiencing initial infection with this virus was higher than expected and that the character of the clinical picture of the disease had changed. Records of patients with herpes infections attending the Oral Medicine clinic covering a 3-year period were examined and the clinical and virological data analyzed. Diagnosis was based on clinical appearance, history, and viral identification with culture or detection of viral DNA by means of the polymerase chain reaction. Records of 60 patients (34 female) were included in the study (mean age, 23.1 years; range, 2 68 years). No patients were known or suspected to be positive for human immunodeficiency virus, none was known to be immunocompromised, and 38 patients (mean age, 16.6 years; 21 female) were diagnosed as having primary herpetic gingivostomatitis. Eighteen patients (mean age, 36.2 years; 11 female) had lesions of recurrent herpes simplex infection present on the oral mucosa. Primary infection with herpes simplex virus was more common in young adults than had been expected. Recurrent infections appeared on the oral mucosal even in otherwise healthy patients, and the clinical course of these infections in this age group sometimes followed a more severe course than that seen in young children.