Context: Biological material reflecting the in vivo composition of markers provides a high potential for biomarker discovery. Objective: We compared the serum proteome following heat-and nitrogen-preservation, with and without subsequent storage at room temperature. Materials and methods: Serum samples were collected, treated and analysed by two-dimensional gel electrophoresis. Protein spots were identified and confirmed by two mass spectrometry approaches (MALDI & ESI) and subjected to Ingenuity Pathway Analysis. Results: We revealed 24 differentially expressed proteins (p.05) between nitrogen and heat preservation, and 87 between nitrogen and heat preservation with subsequent storage for 120h at room-temperature. Mass spectrometry identified 25 polypeptides. Pathway analysis resulted in networks maintaining Cellular Assembly and Organization, Movement and Maintenance. Conclusion: Heat-stabilization does not substantially change the short-term proteome composition of serum compared with nitrogen treatment. However, heat-stabilization alone seems insufficient for long-term sample preservation for serum samples. We identified transthyretin and apolipoprotein A-IV as sample quality markers.