Homogeneous fluorescence assays for detection of nucleic acids are widely used in biological sciences. Typically, probes such as molecular beacons that rely on distance-dependent fluorescence quenching are used for such assays, Less attention has been devoted to tethering a single kind of fluorophores to oligonucleotides and exploiting hybridization-induced modulation of fluorescence intensity for nucleic acid detection. Herein, thermal denaturation experiments and fluorescence properties of oligodeoxyribonucleoticles containing one or more 2 '-N-(pyren-1-yl)carbonyl-2 '-amino-LNA monomer(s) X are described. These pyrene-functionalized 2 '-amino-LNAs display large increases in thermal stability against DNA/RNA complements with excellent Watson-Crick mismatch discrimination. Upon duplex formation of appropriately designed 2 '-N-(pyren-1-yl)carbonyl-2 '-amino-LNA probes and complementary DNA/RNA, intensive fluorescence emission with quantum yields between 0.28 and 0.99 are observed. Quantum yields of such magnitudes are unprecedented among pyrene-labeled oligonucleoticles. Molecular modeling studies suggest that the dioxabicyclo[2.2.1]heptane skeleton and amide linkage of monomer X fix the orientation of the pyrene moiety in the minor groove of a nucleic acid duplex. Interactions between pyrene and nucleobases, which typically lead to quenching of fluorescence, are thereby reduced. Duplexes between multiple modified probes and DNA/RNA complements exhibit additive increases in fluorescence intensity, while the fluorescence of single stranded probes becomes increasingly quenched. Up to 69-fold increase in fluorescence intensity (measured lambda(em) = 383 nm) is observed upon hybridization to DNA/RNA. The emission from duplexes of multiple modified probes and DNA/RNA at concentrations down to less than 500 nM can easily be seen by the naked eye using standard illumination intensities.