Hoechst 33342 (Hydrochloride) is part of the Hoechst family of fluorescent stains that also includes Hoechst 33258 and 34580. Hoechst 33342 (Hydrochloride) is a cell-permeable, fluorescent dye that is recommended for staining and visualization of cell nuclei in live or fixed cells. The excitation of Hoechst 33342 (Hydrochloride) occurs around an ultraviolet wavelength of 350 nm, with maximal emission occurring at 461 nm, emitting a blue/cyan fluorescent light. Compared to the other Hoechst stains, Hoechst 33452 is more readily cell-permeable due to the presence of an additional lipophilic ethyl group (Bucevičius et al.). For live cultures, Hoechst 33342 (Hydrochloride) is recommended to be used in place of DAPI, as it is less toxic and more capable of preserving cell viability after staining. Hoechst 33342 (Hydrochloride) may also be used as a nuclear counterstain in fixed samples.