Thermodynamic analysis provides access to the determinants of binding affinity, enthalpy and entropy. In fragment-based drug discovery (FBDD), thermodynamic analysis provides a powerful tool to discriminate fragments based on their potential for successful optimization. The thermodynamic data generated by FBDD studies can in turn be used to better understand the forces that drive biomolecular interactions. In this review, the technologies that enable thermodynamic analysis of fragment-protein complexes are discussed. In addition, the available thermodynamic data on fragment-protein complexes are summarized and several key studies which highlight the role of thermodynamics in FBDD are discussed in more detail. Although, thermodynamic analysis is not yet applied widely within the FBDD field, the first success stories are starting to appear, exemplifying its value in the development of a more efficient fragment optimization process and a better understanding of ligand-protein interactions. © 2010 Elsevier Ltd. All rights reserved.