This volume is number four in a series of proceedings volumes from the International Symposia on Fractals in Biology and Medicine in Ascona, Switzerland. It highlights the potential that fractal geometry offers for elucidating and explaining the complex make-up of cells, tissues and biological organisms either in normal, abnormal and tumoral conditions. It discusses present and future applications of fractal geometry, bringing together cellular and molecular biology, engineering, mathematics, physics, medicine and other disciplines and allowing an interdisciplinary vision. The book should be of interest to researchers and students from molecular and cell biology, biomedicine, biomathematics, analytical morphology, immunology and neurology who are interested in the combination of mathematics and life sciences.