Synthesis of fluorescent P-hydroxybinaphtylphosphole-oxide or-sulfide was achieved by trapping a binaphtyl dianion with methyl dichlorophosphite or P-(N,Ndiethylamino)dichlorophosphine, followed by oxidation or sulfuration of the P-center. After saponification or acid hydrolysis, the P-hydroxyphospholes were coupled to peptides using the coupling agent BOP, under the conditions required for the synthesis in solution or on a solid support. This new method was illustrated by the labeling of the JMV2959, a potent antagonist of the Growth Hormone Secretagogue Receptor type 1a (GHSÀ R1a). The labeled conjugates were used to characterize GHSR ligands by competition assays, based on Fluorescence Resonance Energy Transfer (FRET). Such P-hydroxyphosphole-oxide or-sulfide constitute a promising new class of compact fluorophores with large Stokes shift, for labeling biomolecules by grafting through the phosphorus atom.