Spirulena Platensis, a blue-green algae, has been recognized and used worldwide as a traditional source of protein in the food industry. The uses and mass cultivation of this algae have risen substantially due to an increased understanding of its biological systems. This text contains detailed descriptions of both the biology and the biotechnological uses of Spirulena Platensis. Part One focuses on the physiology, morphology, photosyntheses and genetics of laboratory cultures. Part Two discusses the practical uses in biotechnology industries, such as: the cultivation on flat-plate reactors; mass cultures outdoors; uses in wastewater treatment and the use of biomass. It offers critiques of the problems encountered and discussions of the future commercial prospects for large-scale production.