The article describes a new database (ProtNA‐ASA), which combines the data on conformational parameters of nucleic acids and calculations of the accessible surface area (ASA) of nucleic acid atoms in protein‐DNA/RNA complexes. As for October 2008, the database contains 214 DNA‐protein and 28 RNA‐protein non‐homologous complexes. The database provides structural parameters that describe local geometry of base pairs and base‐pair steps as well as backbone torsion angles. Additionally, total ASA of DNA/RNA atoms and the accessible area of atoms in the minor and major grooves are calculated. ProtNA‐ASA database facilitates studying the relationship between the DNA/RNA conformation and availability of atoms for contact with proteins either in major or in minor groove for different nucleotides. Such an analysis is important for understanding the principles of molecular recognition including indirect sequence readout. The database is publicly available for use at http://www.protna.bio‐page.org. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010