Nuclear staining in fungi has been difficult because of their low DNA content. DNA intercalating fluorochromes offer a quick, specific, and highly reproducible method for the staining of nuclei both in living and fixed fungal mycelium and spores. There are a number of DNA-intercalating fluorescent compounds such as acridine orange, quinacrine mustard, acriflavin, mithramycin, auramine O, olivomycin A, and ethidium bromide, which bind very specifically to the nucleus. The acridine orange bound to DNA fluorescens green whereas its complex with RNA gives brick red fluorescence. Mithramycin is inert towards RNA and protein but fluoresces yellow when bound to double stranded DNA in the presence of Mg. The specific binding and fluorescent properties of mithramycin make it possible to stain fungal nuclei in a rapid one step procedure. Acriflavin is specific for DNA, the chromosomes stain well and ribosomal RNA rich nucleolus appears as a ghost.