Label-free biosensing based on metallic nanoparticles supporting localized surface plasmon resonances (LSPR) has recently received growing interest (Anker, J. N., et al. Nat. Mater. 2008, 7, 442-453). Besides its competitive sensitivity (Yonzon, C. R., et al. J. Am. Chem. Soc. 2004, 126, 12669-12676; Svendendahl, M., et al. Nano Lett. 2009, 9, 4428-4433) when compared to the surface plasmon resonance (SPR) approach based on extended metal films, LSPR biosensing features a high-end miniaturization potential and a significant reduction of the interrogation device bulkiness, positioning itself as a promising candidate for point-of-care diagnostic and field applications. Here, we present the first, paralleled LSPR lab-on-a-chip realization that goes well beyond the state-of-the-art, by uniting the latest advances in plasmonics, nanofabrication, microfluidics, and surface chemistry. Our system offers parallel, real-time inspection of 32 sensing sites distributed across 8 independent microfluidic channels with very high reproducibility/repeatability. This enables us to test various sensing strategies for the detection of biomolecules. In particular we demonstrate the fast detection of relevant cancer biomarkers (human alpha-feto-protein and prostate specific antigen) down to concentrations of 500 pg/mL in a complex matrix consisting of 50% human serum.