A button battery inserted in the nose of children is an unusual foreign body which is capable of causing extensive tissue damage, resulting from electrical and chemical burns. We report a case of button battery in the nose of a 4-year-old boy presenting with unilateral nasal discharge, and necrosis in the septum and turbinate of the right nasal cavity. Mercury level in concentrated urine was within normal limit. Microscopic examination disclosed extensive liquefaction necrosis with calcification and fibrosis. Numerous dark brown to black granules were noted in the elastic and collagen fibers and interstitium. Dark-field examination of the section revealed brilliantly refractile granules. Polarized microscopy failed to show the granules. Most brown pigments reacted to prussian blue. Tissue mercury analysis yielded a mercury content of 8.01 ppm. We report this case to emphasize the hazards of button battery impaction and to draw attention to the significance of the problem through histopathologic examination.