The present volume III/40C "Nuclear Magnetic Resonance Data, Chemical Shifts and Coupling Constants for Hydrogen-1, Heterocycles" appears as a supplement volume to Landolt-Bornstein's New Series Group III, Volume 35, Subvolume C, Part 2 and provides NMR data published in the years 2000-2003. Included in this volume are all kinds of heterocycles. The complete volume, including links to the original citations, is also available online: you can navigate through the electronic version of this volume starting from the SpringerMaterials - The Landolt-Bornstein Database website www.springermaterials.com; simply select the volume from the electronic "Bookshelf" and jump directly into the PDF data file of interest or search for entries by the powerful search engine. The editors wish to express their thanks to the author Mukesh Jain for this excellent volume which appears as supplement more than seven years after the corresponding volume of Landolt-Bornstein's volume III/35C, Part 2 "NMR Data, Chemical Shifts and Coupling Constants for Hydrogen-1, Heterocycles". The encouraging and never-ending support of K. Sora and R. Muenz from Springer-Verlag is kindly acknowledged. The publisher and the editors are confident that this volume will increase the use of the Landolt-Bornstein. Osnabruck, Jaipur, December 2009 The Editors Editors Gupta, R.R. deceased, formerly Department of Chemistry Rajasthan University Jaipur-302004, India Gupta, V. A-13, Jai Jawan Colony-1 Tonk Road Jaipur-302018, India Lechner, M.D. Institut fur Physikalische Chemie Universitat Osnabruck D-49069 Osnabruck, Germany Author Hydrogen-1 NMR data Jain, M.