VADAR is a comprehensive web server for quantitative evaluation of protein structure quality. It accepts PDB formatted files or PDB accession numbers as input and calculates, identifies, graphs, reports, and evaluates a large number (>30) of key structural parameters for individual residues and the entire protein. These parameters include excluded volume, accessible surface area, backbone and side chain dihedral angles, secondary structure, hydrogen bonding partners, hydrogen bond energies, steric quality, solvation free energy, and local and overall fold quality. VADAR is freely accessible at http://redpoll.pharmacy.ualberta.ca/vadar. Proteins are complex entities, and quantitatively assessing their structure quality is important due to the growing number of structures in the PDB. Several programs like DSSP, WHATIF, and PROCHECK have been developed for this purpose, but none calculate all structural descriptors in a single pass. VADAR is designed to calculate and present a wide range of structural parameters, including those not covered by existing programs. VADAR consists of a front-end web interface (Perl and HTML) and a back-end for calculation (C and Fortran). It processes PDB files or accession numbers and provides detailed tables and graphs for structure evaluation. The server generates four sets of detailed tables and five sets of scatter plots or line graphs. These outputs help identify structural problems in newly determined protein structures. VADAR evaluates various structural parameters, including secondary structure, hydrogen bonds, excluded volume, accessible surface area, and fold quality. It uses multiple methods to identify secondary structure and reports on beta-turns, hydrogen bonding, and other structural features. The server also provides statistical analyses and quality indices for overall structure assessment. The STATS tables compile data from other tables to generate global statistics for structure quality. These tables include limits and variations for structural parameters derived from known high-resolution structures. VADAR also generates graphical outputs for visual assessment of protein structure quality. VADAR is a valuable tool for evaluating protein structures determined by X-ray crystallography, NMR spectroscopy, 3D-threading, or homology modeling. It complements existing structure assessment programs by providing a comprehensive set of structural parameters and quality indices. The server is freely accessible and provides detailed information for users to assess protein structures.VADAR is a comprehensive web server for quantitative evaluation of protein structure quality. It accepts PDB formatted files or PDB accession numbers as input and calculates, identifies, graphs, reports, and evaluates a large number (>30) of key structural parameters for individual residues and the entire protein. These parameters include excluded volume, accessible surface area, backbone and side chain dihedral angles, secondary structure, hydrogen bonding partners, hydrogen bond energies, steric quality, solvation free energy, and local and overall fold quality. VADAR is freely accessible at http://redpoll.pharmacy.ualberta.ca/vadar. Proteins are complex entities, and quantitatively assessing their structure quality is important due to the growing number of structures in the PDB. Several programs like DSSP, WHATIF, and PROCHECK have been developed for this purpose, but none calculate all structural descriptors in a single pass. VADAR is designed to calculate and present a wide range of structural parameters, including those not covered by existing programs. VADAR consists of a front-end web interface (Perl and HTML) and a back-end for calculation (C and Fortran). It processes PDB files or accession numbers and provides detailed tables and graphs for structure evaluation. The server generates four sets of detailed tables and five sets of scatter plots or line graphs. These outputs help identify structural problems in newly determined protein structures. VADAR evaluates various structural parameters, including secondary structure, hydrogen bonds, excluded volume, accessible surface area, and fold quality. It uses multiple methods to identify secondary structure and reports on beta-turns, hydrogen bonding, and other structural features. The server also provides statistical analyses and quality indices for overall structure assessment. The STATS tables compile data from other tables to generate global statistics for structure quality. These tables include limits and variations for structural parameters derived from known high-resolution structures. VADAR also generates graphical outputs for visual assessment of protein structure quality. VADAR is a valuable tool for evaluating protein structures determined by X-ray crystallography, NMR spectroscopy, 3D-threading, or homology modeling. It complements existing structure assessment programs by providing a comprehensive set of structural parameters and quality indices. The server is freely accessible and provides detailed information for users to assess protein structures.