A nucleic acid staining reagent is used for visualization of nucleic acids in a gel and for analysis of nucleic acids separated by electrophoresis. Ethidium bromide is widely used staining reagent in nucleic acid staining and is positioned as a standard for this purpose. However, as ethidium bromide has a mutagenic potential, caution should be exercised when handling it. Therefore, a new, highly safe nucleic acid staining reagent, SAFELOOK™, has recently been developed. Fujifilm Wako provides both ethidium bromide and highly safe nucleic acid reagents.