Clinical proteome analysis will almost inevitably be confronted with blood constituents. Purified plasma, serum, cell or tissue samples may easily be contaminated with some other constituents, affecting the final proteome analysis result. To recognize proteins which are potentially indicative for the presence of major blood constituents, we purified T cells, monocytes, neutrophils, erythrocytes, platelets and plasma and performed comparative proteome profiling employing 2D-PAGE in addition to shotgun proteomics. By mass analysis, 594 different proteins were identified in the 2D gels. Six of the 594 proteins displayed a highly specific expression pattern. A total of 1774 proteins were identified by shotgun proteomics, including 50 proteins with highly specific expression patterns. Indeed, proteins specific for each of the constituents were successfully identified. All protein lists including mass spectrometry details and expression specificity are freely available via the PRIDE database and the CPL/MUW database. The present protein maps of each of the constituents may serve as references for comparative analyses and will aid the interpretation of proteome profiles of clinical samples.