The plasma proteins represent the most thoroughly catalogued group of human proteins. High-resolution two-dimensional electrophoresis has allowed the construction of comprehensive maps of the plasma proteins and makes possible the construction of a Protein Index database covering their molecular and other properties. So far, we have identified 40 polypeptide components on the plasma protein map, leaving perhaps 100 proteins detected but unidentified. This proposal concerns an effort to identify as many of the remaining known proteins as possible, and to begin collection of pertinent molecular data for each protein in order to create a useful Human Plasma Protein Index. Both experimentally derived and literature derived data will be included. This database will be made available online to researchers concerned with plasma protein analysis.