Less than a decade has elapsed since the publication in 2000 of the first anthology devoted to lipocalins (Biochim Biophys Acta 1482, 2000), and only a few years since the first Lipocalin International Symposium in Copenhagen in 2003 (Benzon Symposium no. 50 The Lipocalin Protein Superfamily, Copenhagen, 2003) and the introduction of a public lipocalin website (http: //www.jenner.ac.uk/lipocalins.htm). In spite of all these recent joint actions from the lipocalin community, the need for another anthology has been expressed. Many new exciting publications have been issued during the past five years, partially outdating the 2000 BBA lipocalin anthology. Likewise, the three events mentioned above have undoubtedly had a positive effect upon lipocalin research and the exchange of research information. As a result the community of lipocalin researchers is highly motivated to continue such pan-lipocalin activities. Several of the chapters in this volume are reviews of groups of lipocalins with a similar phylogenetic or tissue distribution (Chapters 4-6, 12 and 13). Furthermore, two chapters discuss the evolutionary and structural relationships between the lipocalins (Chapters 2 and 3) and the penultimate three chapters are treatises on themes in lipocalin research: receptors, allergy, and clinical diagnosis (Chapters 14-16); the final chapter discusses how lipocalin research might go in future."