Recent studies have suggested that esophageal HPV infection could be a risk factor for esophageal squamous-cell carcinoma. The aims of our study were to assess the presence of HPV esophageal infection among French patients with esophageal squamous-cell carcinoma and to compare the prevalence of this infection among control patients exposed to similar known risk factors (alcohol and tobacco) and among non-exposed control patients. All patients had the following investigations: serum immunoglobulin level, T-lymphocyte subsets, cutaneous anergy test and endoscopy with biopsies from tumoral and normal areas. Three different methods were used for HPV-infection diagnosis: histological score, in situ hybridization intended for detection of HPV types 6, 11, 16, 18, 31 and 33, and dot blot intended for detection of HPV types 6/11 and 16/18. Five out of 12 patients with esophageal carcinoma had HPV esophageal infection. This infection did not result from impaired immune status. The most frequently observed types are HPV 16/18. None out of 17 exposed controls and only 1 out of 7 nonexposed controls had HPV esophageal infection (p less than 0.01). HPV infection may be implicated in the development of esophageal squamous-cell carcinoma in association with known risk factors.