For the Egyptians, bread was and still one of the most important foods. It is consumed daily. As a result, the ancient Egyptians in later periods were preoccupied with producing bread through a number of processes. One of these steps is the grinding, in order to turn grain into flour needed to make bread. Grain grinding, or milling, was a significant task that was done in almost every ancient Egyptian home. The grinding of grain was done through mills or millstones that evolved from era to era. Hence, this paper sheds light on mills used in grinding grains in Ptolemaic and Roman Egypt. It includes various mill kinds and who owns them. It also takes into account the kinds of grains that mills grind as well as mill leases. After that, it looks at the archeological evidence for mills in Ptolemaic and Roman Egypt. The researchers will depend on literary and non-literary texts in addition to archaeological evidence in Egypt during the Ptolemaic and Roman Period. Historical and analytical study will be used to examine documents in addition to descriptive study for the archaeological evidences of mills. The results reveal that mills of grain played an important role in the daily life of Graeco-Roman Egypt; they were used for producing flour. Different types of mills especially the Theban mills were used. Ownership of mills varied from individual households to temples and government-affiliated mills in cities.