Mixmer LNA/DNA fluorescent probes containing the 1-(phenylethynyl)pyrene fluorophore attached to 2-arabino-uridine were synthesized and studied. The conjugates displayed significantly higher hybridization affinity to target DNA, increased fluorescence quantum yields of single-stranded oligonucleotides and their duplexes, and improved ability to form an interstrand excimer compared to analogous non-LNA probes. © 2011 American Chemical Society.