Guanidino compounds comprise Creatine, Arginine, and the Guanidines. Since 2001 there have been over 2000 published articles with the names of these compounds in the title. One can go to any nutrition or health food store and buy these as supplements because it is believed they improve health and athletic performance. This volume includes an up-to-date summary of the scientific and clinical aspects of essentially all the biologically active Guanidino Compounds. The articles summarize the current scientific knowledge of these compounds with reference to relevant clinical conditions, and discuss the chemical, biological, and clinical functions of these compounds.