A triple staining procedure was developed to evaluate bull spermatozoa using flow cytometry. Flow cytometric estimates of cell viability, measured by propidium iodide (PI) exclusion, and acrosomal integrity, measured by Pisum sativum agglutinin (PSA) binding acrosomal contents, were equivalent to estimates made by using standard laboratory assays. Mitochondrial function, measured by rhodamine 123 (R123) fluorescence, was depressed by the mitochondrial inhibitors rotenone (64%) or monensin (52%), establishing that mitochondrial damage can be detected. Dilauroylphosphatidylcholine (PC12) or lysophosphatidylcholine (LPC) was used to destabilize sperm membranes. When challenged with 15-30 microM PC12, selective exposure of PSA binding sites occurred without induction of PI uptake or loss of R123 staining. However, PC12 concentrations greater than 60 microM resulted in a loss of R123 fluorescence intensity. In contrast, greater than 1200 microM LPC was required to expose PSA binding sites, which also resulted in PI uptake. By using flow cytometry, these three stains in combination can be used to correlate three different features simultaneously on individual spermatozoa and assay thousands of cells per sample without extensive preparation.