Incidences of swallowing lithium batteries have been increasing. More severe tissue damage may be produced by the flow of electric current through tissue due to a lithium battery than a button alkali battery, because the former has the higher voltage of 3V. In this study, model CR2032 lithium batteries were fixed in the esophagus of 5 adult mongrel dogs for 15 or 30 min or 1, 2 or 5 h. On microscopical examination of the esophagus 15 min after fixation of the battery, necrosis was demonstrated from the lamina propria mucosa to the inner muscular layer. Thirty min after fixation of the battery, the esophageal epithelium had completely disappeared to form a blackish-brown area and the outer muscular layer was partially necrosed. Histological findings after 1, 2 or 5 h were similar to those after 30 min, and the blackish-brown area became larger with time. The necrosis extended to the trachea after 1 h. The necrosis developed sooner in tissue in contact with the lithium battery. An ingested lithium battery appears to be more dangerous than a button alkali battery unless it is removed quickly.