This volume, based on the International Congress Creatine: From Basic Science to Clinical Application, held in Milan on June 4, 1999, outlines the physiological role of creatine in the human body as well as its possible role in different pathological conditions. Creatine is already used as a dietary supplement to augment muscle performance in healthy individuals and inpatients with immobilizing diseases, such as complex fractures. There is also an increasing interest in its administration in a growing number of clinical conditions. A specific deficit of endogenous synthesis of creatine which responds to high dosage exogenous supplementation has been described. In cardiac failure and in chronic obstructive pulmonary disease, creatine improves the contractility of the muscular system. Promising effects of this substance have also been described in animal models of neurodegenerative disorders, such as amyotrophic lateral sclerosis, and in some mitochondrial cytopathies. This volume is of obvious interest to basic scientists working on the physiology of creatine and to clinicians interested in its medical indications.