The effects of ACh, ATP and high K+ on intracellular calcium concentration Ca2+ in outer hair cells (OHC) of the guinea pig cochleae were observed with the use of Ca2+ sensitive dye Fluo-3 and laser scanning confocal microscope. Ca2+ increase induced by these chemicals had individual temporal and spatial features. Moreover, high K+ solutions induced contraction and bending of OHC too. Taking advantage of the "optical sectioning" facility of confocal microscopy, morphography of Fluorescein-labelled living OHC and PI-dyed nuclei was reconstructed three-dimensionally. The application of confocal microscopy in OHC physiological and morphological research was discussed.