The present study evaluated ethidium bromide, a nucleic acid-specific fluorescing stain for cochlear applications. Tissue exposed to acoustic stimulation did not exhibit the loss of fluorescence in hair cells described in studies on other fluorescing stains. The ethidium bromide fluorescence technique was, however, found to be useful in detecting subtle damage in cell nuclei even before gross structural alterations in cochlear cytoarchitecture appeared. The implications of the use to ethidium bromide staining for histologists are discussed.