This review article is concerned with (i) proteomic sample preparation including among other things the depletion of high-abundance proteins and the concentration of low-abundance proteins and (ii) their subsequent prefractionation for further analysis. Subjects (i) and (ii) are essentials for in-depth proteomic analysis by multidimensional liquid-phase separation techniques (e.g. multidimensional electrophoresis and LC in various formats) followed by mass spectrometric identification and bioinformatic. More than 90 papers published in the period covering early 2000 to the present have been reviewed. It should be noted that this review article is by no means exhaustive, and the aim was to rather provide a concise description of the latest developments in the field.