Dryness has harmful effect on the harvested autogenous bone. But there was no report how the bone cells response to the drying condition and recuperate after exposure. Cytotoxic effect of dryness on the osteoblast-like cells were examined from 18- day chick calvaria. The cells were rinsed with lactated Ringer solution or lactated Ringer solution with 10% fetal bovine serum to see whether the added serum could help the cells live longer. Cultured cells were exposed to room air for period of time ranging from 0 minute to 35 minutes and viability was determined using the MTT test. Cultured cell death increased with the increase of exposure time to air between 25 and 30 minutes. No live cells existed after 35 minutes exposure. Lactated Ringers solution containing 10% fetal bovine serum did not prolong the survival time of osteoblast-like cells compared with lactated Ringers solution alone. These results suggest that the drying of bone cells that occurs in the operating room, especially after a prolonged reconstructive procedure, may severely damage the cell viability of exposed bone or grafted bone and thereby compromise the fusion rate.