Updated project metadata. Clinical proteomics research is in part limited by the availability of clinical samples. However, large biobanks exist worldwide containing formalin-fixed and paraffin embedded samples and samples stored in RNAlater. The extraction of proteins for proteome analysis from samples prepared by either method has been demonstrated. However, the impact of the preservation method on the result of a quantitative proteome analysis remains largely uninvestigated. We, therefore, conducted a proteome analysis of human colon mucosal biopsies where the material had been preserved accordingly. Twenty-four colon mucosal biopsies were extracted from the sigmoideum by endoscopy from two participants. The biopsies were either directly-frozen, stabilized in RNAlater, or stabilized by formaldehyde fixation immediately or incubated for 30 min to simulate a clinical situation, followed by paraffin embedding. The impact of the preservation method on the result of a proteome analysis was characterized by high throughput gel free quantitative proteomics.