Histology, cytology and other related scientific disciplines study the microscopic anatomy of tissues and cells. In order to demonstrate a good tissue and cellular structure, the samples need to be stained in a correct manner. Orange II powder dye is intended for microscopy staining using different methods. It is most commonly known as cytoplasmic staining counterstain, and recently it has been used for quantitative histochemistry protein assessment. Although rarely, it is also used as a part of certain polychromatic dyes.