Preface It is pleasure to present the fourth 2009 issue of the European Respiratory Monograph (ERM). For the second time, an issue is dedicated to interstitial lung diseases the first ERM on this topic was published in 2000. As this is a rapidly growing field within respiratory medicine, with continuous novel research achievements, there is high motivation to publish a new ERM on interstitial lung diseases after nine years. The current issue is somewhat differently structured compared with the former version. The editors have chosen an interesting approach in which they, after an introductory chapter written by two prominent scientists within the field, T.E. King Jr and U. Costabel, in the first section have focused on current challenges and questions, in the second section on diseases and in the third part have addressed some international aspects of this heterogeneous group of diseases. In the first part, aspects of morphology, cell biology and biomarkers have been extensively covered, as well as clinical topics such as exercise testing and clinical trials. The disease section has been expanded to include specific chapters on occupational interstitial lung diseases, drug-induced infiltrative lung diseases and interstitial lung diseases in children. In the third section, the situation regarding interstitial lung diseases in India and the Far East is addressed. In these areas, interstitial lung diseases are most likely under diagnosed, due to low awareness and low access to modern technical equipment such as computed tomography. As the knowledge within the area of interstitial lung diseases is growing and the interest from pulmonary clinicians is increasing, it is felt timely now to publish this ERM. I very much appreciate that two of the most outstanding experts in the field accepted to serve as guest editors for this issue and that they were able to engage so many of their expert colleagues in this project. We know, from a recently performed market research survey, that the ERM is highly appreciated and read by the members of the European Respiratory Society, and it is therefore a pleasure to present this new ERM covering a topic that will be of immense interest to almost everyone who has an interest in pulmonary medicine. Editor in Chief, K. Larsson Eur Respir Mon, 2009, 46, viii. Printed in UK - all rights reserved. Copyright ERS Journals Ltd 2009 European Respiratory Monograph ISSN 1025-448x. viii