SYBR Safe is a cyanine dye used as a nucleic acid stain in molecular biology. SYBR Safe is one of a number of SYBR dyes made by the Life Technologies Corporation. SYBR Safe binds to DNA. The resulting DNA-dye-complex absorbs blue light (û<sub>max</sub> = 509 nm) and emits green light (û<sub>max</sub> = 524 nm).
SYBR Safe is marketed as a safer alternative to ethidium bromide. SYBR Safe has a very similar structure to thiazole orange, which has a methyl group attached to the charged nitrogen, whereas SYBR Safe has an N-propyl group. Thiazole Orange has been shown to be three to four times less mutagenic than ethidium bromide whereas SYBR Safe is four to five times less mutagenic. Additionally, according to the Life Technologies website, SYBR Safe is not lethal in rats at doses as high as 5 g/kg, and rats don't show symptoms of acute toxicity. Thiazole orange does show toxicity at this dose.