The number of investigators focusing their attention on lactoferrin has increased dramatically in recent years. Lactoferrin is a protein with more than one known structure and a number of proposed biological functions, including several with important regulatory consequences. In many ways it has been an easy pro tein to investigate; however, there have been difficulties under standing specific structure / function relationships, particularly as it functions in vivo. Research funding dedicated to this protein has previously been limited, but is now increasing. As lactoferrin begins to emerge formally as a protein of significance to the medi and industry, it is more important than ever to coor cal profession dinate and integrate research efforts whenever possible and to share the results of these efforts within the expanding array of medical and scientific diSciplines involved. It was our intention to provide a forum to summarize and disseminate the most recent advances in this field. Included in Lactoferrin: Interactions and Biological Functions are selected presentations representing the many disciplines involved in defining lactoferrin function in terms of its known structural features, including its carbohydrate side-chains, receptor binding sites, its capacity to bind different metal ions, and other newly discovered bioactive domains. Several of the possible physiologi cal functions of lactoferrin are described and summarized in detail, including the role of laetoferrin in bacterial killing, its in volvement in cell growth and proliferation, in the modulation of immune function, and in iron absorption.