Herpetic gingivostomatitis is the most common specific clinical manifestation of primary herpes simplex infection in childhood. The aim of the present study was to describe the clinical signs, symptoms, viral shedding, serologic findings, and complications in community-acquired gingivostomatitis. We prospectively followed children with herpes simplex type 1 gingivostomatitis lasting less than 72 hours. Clinical examination and viral culture were repeated every 2 to 3 days as long as symptoms or signs persisted. Thirty-six children (ages 12-77 months) were included in the study. Mean duration of oral lesions was 12.0+/-3.4 days; extraoral lesions (in 26 children), 12.0 +/-3.9 days; fever, 4.4+/-2.4 days; and eating/drinking difficulties, 9.1+/-3.0 and 7.1+/-3.1 days, respectively. In all children, viral cultures of the oral lesions were positive for herpes simplex virus (HSV) type 1; viral shedding persisted for a mean of 7.1+/-2.5 days (range 2-12 days). The main complications were dehydration, with three children hospitalized for intravenous rehydration, and one case of secondary bacteremia. Herpetic gingivostomatitis is a relatively severe manifestation of primary HSV type 1 infection in young children.