Abstract: The damage effects of the turbulent shear stresses in the bulk liquid and the gas bubbles on hybridoma cells were examined by using the high speed agitated tests in the spinner bottles and the sparging tests in a bubble column.It is found that,in the absence of gas bubbles,cell damage can be caused by the stresses in the bulk turbulent liquid only when the Kolmogorov turbulent eddy sizes are similar to or smaller than the cell size,While in the presence of gas bubbles,cells are mainly destroyed by these bubbles.Increasing the gas flow rate and decreasing the bubble size result in increased cell death. In addition,the physical mechanism governing cell damage in bioreactors is also discussed.