PURPOSE: To determine the etiologies of esophageal symptoms in human immunodeficiency virus (HIV)-infected patients failing antifungal treatment. METHODS: Between August 1, 1990 and December 31, 1994, all HIV-infected patients seen at a large inner-city hospital who had esophageal complaints despite being on antifungal therapy were prospectively evaluated for the cause of symptoms. Thus, the population studied included patients given empiric antifungal therapy for esophageal symptoms and patients who developed symptoms while on long-term antifungal therapy. Endoscopy was performed in all patients. The cause of symptoms was determined by the clinical, endoscopic, and pathologic findings, and follow-up after treatment. RESULTS: Over the 53-month study period, 74 patients failing empiric antifungal therapy were identified. The majority (77%) of these patients had esophageal ulcers; 25 patients had idiopathic ulcers and 24 had cytomegalovirus. In 2 patients, Candida was present with other causes of ulcerative esophagitis. Candida esophagitis alone was diagnosed in only 3 patients. No endoscopic abnormalities were observed in 14 patients (19%). An additional 24 patients developed esophageal symptoms while receiving antifungal therapy; endoscopic findings in these patients included ulceration in 16 (67%), Candida esophagitis alone in 2, and normal in 6. Empirically treated patients in whom odynophagia was not the only symptom, those with dysphagia alone, and those with a CD4 count >100/mm3 were less likely to have an endoscopic diagnosis. CONCLUSIONS: Esophageal ulceration is the most common cause of esophageal symptoms in HIV-infected patients failing empiric antifungal therapy and those developing symptoms while receiving antifungal agents. Given these findings, endoscopy should be the test of choice for these nonresponders, rather than escalating the dose of antifungal agent, adding other empiric treatments, or performing barium esophagography.