The inner hair cell stereocilia of the guinea pig cochlea was examined under a scanning electron microscope (SEM) after loud tone exposure onto the ear drum of the animal. Before and after guinea pigs were exposed to intensive and continuous tone such as 106 dB SPL in intensity, the functioning of the cochlea was monitored by N1-N2 audiograms. The structural damage of the stereocilia of inner hair cells (IHCs) and outer hair cells (OHCs) was examined using the SEM in x 1500 magnification. The comparison between the functional change of the cochlea and the structural damage of the IHC stereocilia is done by means of photographic observation. It can be shown that the functional change might be related to the structural damage of the IHC stereocilia after intensive acoustic trauma.