The impact of advances in nanotechnology is particularly relevant in biodiagnostics, where nanoparticles based assays have been developed for specific detection of bioanalytes of clinical interest. Gold nanoparticles show easily tuned physical properties, including unique optical properties, robustness, and high surface areas, making them ideal candidates for developing biomarker platforms. Modulation of these physicochemical properties can be easily achieved by adequate synthetic strategies and give gold nanoparticles advantages over conventional detection methods currently used in clinical diagnostics. The surface of gold nanoparticles can be tailored by ligand functionalization to selectively bind biomarkers. Simple and inexpensive methods based on these bio-nanoprobes are presently being expanded to clinical diagnosis as well. In a nutshell, nanoparticles hold great promise in the future of disease diagnostics.