Variability is one of the most critical issues of concern in clinical proteomics. In this issue of Proteomics Clinical Applications, Yoshida et al. [Proteomics Clin. Appl. 2012, 6, 412–417] describe the effects of blood and number of washes on the human glomerular proteome isolated from the kidney by laser microdissection. The blood-derived proteins occupied almost 50% of all the identified proteins in the unwashed samples, whereas varying the number of washes (from 1–5) with PBS yielded only 43–80% of the proteins identified in each sample that were common in all samples. This urges caution to all proteomists to carefully consider sample preservation and preparation for tissue proteome analysis.