Tetramethylrhodamine (TAMRA) is a fluorescent dye that has been popularly used for labeling oligonucleotides. Because of its instability to ammonium hydroxide, TAMRA was first used as TAMRA NHS Ester to label amino-modified oligonucleotides. However, later work showed that TAMRA is stable to UltraMild deprotection and also deprotection with hindered amines, like t-buylamine, so supports and phosphoramidites containing TAMRA were quickly introduced. TAMRA-modified oligonucleotides have established an important role in both Förster resonance energy transfer (FRET) and real-time PCR applications.