During the last years abundant sequence data has become available due to the rapid progress in protein and DNA sequencing techniques. The exact three-dimensional structures, however, are available only for a fraction of proteins with known sequences. For many purposes the primary amino acid sequence of a protein can be directly used to predict important structural parameters. However, mathematical presentation of the calculated values often makes interpretation difficult, especially if many proteins must be analysed and compared. Here we introduce a broad-based, user-defined analysis of amino acid sequence information. The program package is based on published algorithms and is designed to access standard protein data bases, calculate hydropathy, surface probability and flexibility values and perform secondary structure predictions. The data output is in an 'easy-to-read' graphic format and several parameters can be superimposed within a single plot in order to simplify data interpretations. Additionally, this package includes a novel algorithm for the prediction of potential antigenic sites. Thus the software package presented here offers a powerful means of analysing an amino acid sequence for the purpose of structure/function studies as well as antigenic site analyses. These algorithms were written to function in context with the UWGCG (University of Wisconsin Genetics Computer Group) program collection, and are now distributed within that package.