Methyl green (CI 42585) is a cationic or positive charged stain, related to Ethyl Green, that has been used for staining DNA since the 19th century. It has been used for staining cell nuclei either as a part of the classical Unna-Pappenheim stain, or as a nuclear counterstain ever since.In recent years, its fluorescent properties when bound to DNA have positioned it useful for far-red imaging of live cell nuclei. Fluorescent DNA staining is routinely used in cancer prognosis.Methyl green also emerges as an alternative stain for DNA in agarose gels, fluorometric assays and flow cytometry. It has also been shown that it can be used as an exclusion viability stain for cells.Its interaction with DNA has been shown to be non-intercalating, in other words not inserting itself into the DNA, but