Pullulan is one of the most important polysaccharide. It is linear chain of maltotriose repeating units interconnected by alpha linkages. This polysaccharide is easily soluble in water. It is mainly produced by the polymorphic black yeast like micro-fungus Aureobasidium pullulans. A. pullulans widely occurs frequently in wide range of tropical and temperate environment. This polysaccharide is of economic importance with increased application in food, pharmaceutical, agricultural and chemical industries. This book will throw light on the importance of this polysaccharide and its production at laboratory level.