Counterfeiting of coins is an economic problem to states. It took many forms but was not limited to the eras of weakness and the collapse of the economy. Rather, it sometimes took place in some eras of strength. The counterfeit dinar under study is a piece of evidence. It was counterfeited in one of the greatest periods of the First Abbasid Period at the time of Caliph Harun al-Rashid (170-193 A.H./786-809A.D.) in the name of prince Musa ibn Isa of the Abbasid Dynasty who was a ruler of Egypt for the second time. It was minted using a mold dedicated to counterfeit dinars that might be used for an entire set of dinars. The Graeco-Roman Museum in Alexandria, Egypt holds another similar counterfeit dinar.