The authors have treated 44 patients with posterior chronic acid laryngitis. Biopsy was performed in all patients. Characteristic changes typical of the hyper-regenerative or atrophic phase of reflux oesophagitis were identified in all specimens. Gastric hypersecretion was proven in all but two patients. The aetiologic factors of acid posterior laryngitis are gastro-oesophageal reflux, with friction of both vocal processes during phonation and vocal abuse. The preferred therapy is removal of circumscribed lesions with a suitable medical regimen.