Blood serum/plasma samples provide the major source to identify diagnostically relevant or treatment response-related proteins. But its complexity and the enormous dynamic range hinders comprehensive analysis. Therefore, more detailed analysis, in particular, of low-abundant peptides/proteins requires extensive pre-fractionation, which frequently influences the native composition and may lead to a loss of potentially important information. In order to overcome these barriers, we describe an innovative sample preparation tool utilizing combinatorial hexapeptide ligand libraries to efficiently enrich low-abundance proteins with a simple protocol. In contrast to the most common approaches based on the immuno-depletion of antibody-targeted high-abundance proteins, this technology concentrates low-abundance proteins and concurrently reduces the high-abundance species. Thus, the dynamic range is compressed, and low-abundance proteins become more easily detectable. We show how this sample preparation technique can be easily combined with 2D DIGE analysis to enable more comprehensive and quantitative profiling of complex biological samples.