Used in clinical and reproductive laboratories to assess sperm viability. The solution helps differentiate live sperm from dead sperm under a microscope. Eosin dye penetrates dead sperm cells, staining them pink or red, while live sperm remain unstained due to intact cell membranes. This allows technicians to calculate the percentage of viable sperm in a semen sample, which is important for evaluating male fertility and supporting assisted reproductive technologies like IVF and IUI. The method is simple, cost-effective, and widely used in routine semen analysis.