DrugBank is a fully curated drug and drug target database that contains information on nearly 5000 drugs, including > 1200 FDA-approved small molecule and biotech drugs as well as >3200 experimental drugs. Additionally, more than 14,000 protein or drug target sequences are linked to these drug entries. DrugBank is primarily focused on providing both the query/search tools and the biophysical data needed to facilitate drug discovery and drug development. This unit provides readers with a detailed description of how to effectively use the DrugBank database and how to navigate through the DrugBank Web site. It also provides specific examples of how to find chemical homologs of potential drug leads and how to identify potential drug targets from newly sequenced pathogens. The intent of this unit is to give readers some introduction into the field of cheminformatics (the study of chemical information) and to show how cheminformatics can be seamlessly integrated into the field of bioinformatics.