The word proteomics was coined in 1997 to describe the changes in all proteins expressed by a genome. Several sophisticated techniques including two-dimensional electrophoresis, imaging, mass spectrometry, and bioinformatics are used in proteomics to identify, quantify, and characterize proteins. Clinical proteomics is the application ofproteomics techniques to the medical field. The main aim of this methodology is to identify proteins involved in pathological processes and to understand how illness can lead to altered protein expression. Clinical proteomics offers the opportunity and the potential to develop new diagnostic and prognostic tests, to identify new therapeutic targets, and eventually to allow the design of individualized patient treatment. Here we present an overview of proteomics applications to the study of disease and its potential to improve diagnosis and prognosis.