Plasma contains numerous and diverse proteins with existing and potential therapeutic value. Plasma has been used clinically as both a source of purified derivatives for treating diseases such as hemophilia, and as a diagnostic medium. Recent research directed towards mining plasma's true potential takes advantage of state-of-the-art proteomic analytical methods to develop multi-protein, disease-specific biomarker panels to improve the reliability and specificity of diagnostics. Recombinant production and chromatographic purification methods are increasing the yield and safety of traditional plasma derivatives. Emerging cell-based technologies are being applied to discover novel protein activities and identify epitope-specific antibodies that may have clinical promise.