Flow cytometric analysis has been developed to detect tailless sperm with heads detached from the tails at the neck position. When isolated tailless sperm suspension was subjected to flow cytometry, a second sperm population appeared alongside the normal sperm population on light scatter-histogram. The percentage of this second sperm population(85.2%)was in good agreement with that for the tailless sperm(88.7%)determined microscopically, indicating that the second sperm population would correspond to tailless sperm population in the light scatter-histogram. Rates for tailless sperm determined by flow cytometry significantly correlated with those estimated microscopically following exposure of sperm to either sonication(r=0.94, P<0.01), or nitrobenzene(r=0.80, P<0.01). The results indicated the utility of the light scatter-histogram in flow cytometry as a simple and convenient procedure for the detection of tailless sperm induced by chemical compounds.