Dragon is an application for the calculation of molecular descriptors. These descriptors can be used to evaluate molecular structure-activity or structure-property relationships, as well as for similarity analysis and high-throughput screening of molecule databases. Dragon 7.0 is its latest release (2016) and calculates 5,270 molecular descriptors. It also calculates fingerprints and molecular fragments. The list of descriptors includes the simplest atom types, functional groups and fragment counts, topological and geometrical descriptors, three-dimensional descriptors, but also several properties estimation (such as logP) and drug-like and lead-like alerts (such as the Lipinski’s alert). The wide range of different approaches and theories for descriptors calculation, and the correctness and precision of their implementation are ensured by the scientific supervision of the Milano Chemometrics and QSAR Research Group of prof. Roberto Todeschini, author with dr. Viviana Consonni of Molecular Descriptors for Chemoinformatics (the most complete reference for descriptors theory).