Advances in mass spectrometry (MS) instrumentation resulting in higher mass resolution and higher duty cycles have allowed deeper coverages of proteomes. The development of candidate RM 8461 Human Liver for Proteomics was undertaken to provide the community with a sample with suitable complexity for method development and validation, instrument and data validation, and determining identification QC thresholds. Herein we describe a comparison of methods and homogeneity assessment in which candidate RM 8461 Human Liver for Proteomics is solubilized, the proteins reduced, alkylated, digested and the tryptic peptides and their modifications are identified by bottom up LC/MS/MS to assess deep (e.g. thousands of identifications) protein coverage.