Evan's blue is widely used as a vital dye to assess the integrity of biological barriers, particularly the blood-brain barrier. It binds strongly to serum albumin, making it useful for tracing vascular permeability and detecting leakage in tissues. Due to this property, it is commonly employed in research to visualize and quantify disruption in endothelial barriers during inflammation, injury, or disease. It is also used in cell viability assays, where it selectively stains dead cells with compromised membranes, allowing researchers to distinguish live from dead cells under a microscope. In addition, Evan's blue serves as a marker for plasma volume measurement and lymph node mapping in surgical and experimental settings. Its high visibility and low toxicity make it suitable for in vivo imaging and diagnostic procedures in animal models, especially in studies related to tumor biology, neurology, and vascular diseases.