Bread and cereals were an important part of the ancient Iranian diet. The high nutritional value of bread had made bread have a prominent place in the culture of ancient Iranian. Despite this importance, little research has been done about bread in ancient Iran.The question is what role did play bread in the nutrition and culture of ancient Iran and what was the appearance and process of baking bread? The aim of this research is studying the nutritional and cultural status of bread, types of cereals used, types of bread in terms of shape and technique of baking in ancient Iran. This research on the base of purpose is basic research and on the base of the nature and method is historical research, the method of research is descriptive-analytical. Archaeological data, historical sources and religious and mythological texts of ancient Iran were used. Also, the methods that specified in linguistic studies for baking bread in ancient Iran were adapted to the method of baking some traditional breads in present-day Iran. The results of this study showed that cereals were the most important material for baking bread in ancient Iran. Two important advances in the process of baking bread, namely the use of dough to make dough and the use of tandoor for baking bread, occurred in ancient Iran, without abandoning the previous methods of preparing dough and baking bread. As a result, Iranians ate both unleavened bread and sourdough bread, and although the use of ovens made large-scale bread production possible, the old method of baking bread on hot ashes was still used.