UNLABELLED: Amino acid contacts in terms of atomic interactions are essential factors to be considered in the analysis of the structure of a protein and its complexes. Consequently, molecular biologists do require specific tools for the identification and visualization of all such contacts. Graphical contacts (GC) and interface forming residue graphical contacts (IFRgc) presented here, calculate atomic contacts among amino acids based on a table of predefined pairs of the atom types and their distances, and then display them using number of different forms. The inventory of currently listed contact types by GC and IFRgc include hydrogen bonds (in nine different flavors), hydrophobic interactions, charge-charge interactions, aromatic stacking and disulfide bonds. Such extensive catalog of the interactions, representing the forces that govern protein folding, stability and binding, is the key feature of these two applications. GC and IFRgc are part of STING Millennium Suite. AVAILABILITY: http://sms.cbi.cnptia.embrapa.br/SMS, http://trantor.bioc.columbia.edu/SMS, http://mirrors.rcsb.org//SMS, http://www.es.embnet.org/SMS and http://www.ar.embnet.org/SMS (Options: Graphical Contacts and IFR Graphical Contacts).