Every year, the Federation of European Biochemical Societies sponsors a series of Advanced Courses designed to acquaint postgraduate students and young postdoctoral fellows with theoretical and practical aspects of topics of current interest in biochemistry, particularly within areas in which significant advances are being made. This volume contains the Proceedings of FEBS Advanced Course No. 88-02 held in Bari, Italy on the topic "Organelles of Eukaryotic Cells: Molecular Structure and Interactions. " It was a deliberate decision of the organizers not to restrict FEBS Advanced Course 88-02 to a discussion of a single organelle or a single aspect but to cover a broad area. One of the objectives of the course was to compare different organelles in order to allow the participants to discern recurrent themes which would illustrate that a basic unity exists in spite of the diversity. A second objective of the course was to acquaint the participants with the latest experimental approaches being used by in vestigators to study different organelles; this would illustrate that methodologies developed for studying the biogenesis of the structure-function relationships in one organelle can often be applied fruitfully to investi gate such aspects in other organelles. A third objective was to impress upon the participants that a study of the interaction between different organelles is intrinsic to understanding their physiological functions. This volume is divided into five sections. Part I is entitled "Structure and Organization of Intracellular Organelles."