Fluorescence is a very powerful tool for work at the frontier of cell biology, photobiology and bioinstrumentation. The stated aim of the workshop was to highlight the significance of fluorescence work for the understanding of cell and tissue physiology, physiopathology and pharmacology, particulary in terms of the analytical use of fluorescent probes in oncology. In the organization of the workshop a multidisciplinary approach was selected. The purpose of the Advanced Research Workshop (ARW) was to bring together researchers in the various disciplines of tissue optics, imaging, microspectrofluorometry and state of the art probes, in order to explore the full benefits that can be derived in biomedicine through the convergence of these approaches. When applied to in vivo and in situ studies, fluorescence and related optical methods enable us to explore within tissues, cells and organelles photon effects previously understood only in solution photochemistry. Processes which can be studied at the molecular level by photophysics, photochemistry and physical chemistry can be evaluated in living tissue by fluorescence spectroscopy and imaging at the intracellular level in terms of structure and function. Thus, fluorescence adds a new dimension to cell biology and physiology. This approach is now supported by a full and versatile, rapidly growing armamentarium of new selective probes for organelles, enzymes, cations, cytoskeleton and metabolic control.