Neodymium based fluorescence presents several advantages in comparison to conventional rare earth or enzymesubstrate based fluorescence emitting sources (e.g.Tb, HRP) . Based on this fact we have herein explored a Nd-based fluoroimmunoassay. We efficiently detected the presence of an oxidized low-density lipoprotein (oxLDL) in human plasma a well-known marker for cardiovascular diseases, which causes around 30% of deaths worldwide. Conventional fluoroimmunoassay uses time-resolved luminescence techniques, with detection in the visible range, to eliminate the fluorescence background from the biological specimens. By using an immunoassay based on functionalized Y 2O3:Nd3 nanoparticles, where the excitation and emission processes in the Nd3 ion occur in the near-infrared (NIR) region, we have succeeded in eliminating the interferences from the biological fluorescence background, avoiding the use of time-resolved techniques. This yields higher emission intensity from the Nd3-nanolabels and efficient detection of anti-oxidized low-density lipoproteins (anti-oxLDL) by Y2O3:Nd3-antibodyantigen conjugation, leading to a novel biolabeling method. © 2010 Elsevier B.V.