Herpetic esophagitis (HE) associated with human immunodeficiency virus (HIV) is a rare condition mainly reported as isolated cases. We thus decided to study this association and analyze the possible predisposing factors, clinical and endoscopic presentations, and clinical response to treatment. Thirty-four HIV-1-infected patients were identified: 27 had histologically or virologically confirmed HE and seven had probable HE, a retrospective diagnosis based on the efficacy of acyclovir given alone. The median CD4 cell count was 15/mm3. Recent predisposing factors (such as nasogastric procedures, steroid therapy, and anticancer therapy) were noted with regard to 16 of the 34 patients (47%). Odynophagia and/or chest pain occurred in 30 patients (88%). At the time of diagnosis of HE, extraesophageal herpes was found in only 13 patients (38%). Superficial ulcers of the distal third of the esophagus were present in 17 (50%). Among 20 of the 27 patients with confirmed HE that could be evaluated, therapy with acyclovir led to complete resolution in 16 and partial response in 3; 1 patient died of HE. Five patients (15%) suffered confirmed or possible relapses. The mean interval between the diagnosis of HE and death was 8.8 months. Herpes simplex virus may be responsible for ulcerated esophagitis that occurs in the advanced stages of AIDS and that can be safely treated with acyclovir before a definitive diagnosis is made.