Hair cells were dissociated from basila papilla of 7 to 10 week post-hatched chicks (n = 15) by collagenase digestion followed by trituration. Morphological measurements of 215 viable hair cells from 5 chicks were performed. The average dimensions of the cells were: length 20.22 +/- 3.32 microns, width 9.93 +/- 2.01 microns of tall hair cells (n = 164); length 10.97 +/- 2.29 microns, width 14.8 +/- 2.29 microns of short hair cells (n = 30); length = width = 11.93 +/- 1.74 microns of intermediate hair cells (n = 21). Using fluorescein diacetate and propidium iodide, viability of isolated hair cells from another 5 chicks was determined. With excitatory light, fluorescence of viable cells were bright green in 3 hours, while the fluorescence of live cells were attenuated to such an extent that light green shadows were showed up to 5 hours after chicks were decapitated. The results suggested that the criterion of morphological observation and dying of cells should be combined to determine viability of isolated hair cells.