Wright Staining Solution is a mix of an anionic dye eosin, and a cationic dye methylene blue. Wright staining is a widely used technique in histopathology.

Eosin being acidic, bind to the mature red blood cells and eosinophils to give a pink color. While methylene blue is basic and binds to acidic components like basophils, monocytes, and lymphocytes, producing a blue-purple or purple-red color. Neutrophils can react with eosin and methylene blue together and are stained pale purple. Each type of blood cell stains differently and can be distinguished morphologically. Similarly, this solution stains the basic cytoplasm pink, and stains the acidic nuclei purple-red.

Wright staining solution is often used in combination with Giemsa staining solution.