To determine the spectrum of esophageal disease responsible for dysphagia/odynophagia in AIDS patients not responding to current oral antifungals, we studied 49 consecutive patients whose esophageal symptoms failed to improve after a minimum of 3 wk of therapy with oral ketoconazole or fluconazole. An esophageal candidiasis resistant to oral antifungals was the most frequent disease found (22 single infections and four mixed with viruses). Viral esophagitis was identified in 13 cases (eight herpes simplex virus and five cytomegalovirus), and an esophagitis of unknown origin was documented in two patients. Other causes of symptoms included peptic esophagitis (four cases), esophageal stenosis (two cases), and Kaposi's sarcoma of the esophagus (one patient). Most patients with esophageal opportunistic infection experienced prompt relief of symptoms and complete endoscopic resolution on the specific antifungal (amphotericin B or fluconazole iv) or antiviral (acyclovir or gancyclovir iv) therapy, with the exception of those with concomitant fungal and viral infection who responded poorly to treatment. We conclude that most AIDS patients with dysphagia/odynophagia who do not respond to oral antifungals have an opportunistic infection of the esophagus. Nevertheless, specific antifungal or antiviral therapy is worthwhile, because it will eradicate, at least temporarily, the causative pathogens in most such patients.