A deeper appreciation of the nature of molecular interactions between a protein and a ligand would potentially improve the ability of chemists to design drugs. Information about molecular interactions can be obtained from X-ray structures, the number of which has increased rapidly over the past few years. It is therefore proposed to carry out a detailed analysis of the X-ray structures contained within various databases and in particular the Cambridge Structural Database. It is anticipated that this will result in the identification of a number of novel interactions as well as providing a more comprehensive description of well established interactions. Once identified, information about these interactions will be incorporated into a user friendly, relational database with the aim of facilitating the consideration of such information by medicinal chemists in designing novel ligands for proteinaceous enzymes and receptors, for potential use in therapy.