Abstract: A process for characterizing sperm motility and viability by staining a sperm sample with Rhodamine 123 and ethidium bromide, and simultaneously measuring the sperm fluorescence emissions at green frequencies 515-575 nm and at red frequencies 600-650 nm, the green counts being correlated with sperm motility and the red counts being correlated with putative dying or dead cells. Additionally, a sample of sperm can be characterized as to type and normality by staining a sample of sperm with acridine orange and simultaneously measuring the sperm fluorescence emissions at green frequencies 515-575 nm and at red frequencies 600-650 nm.