This research presents an Abbasid commemorative Dirham in the name of Mulahidh and Abbasi ruler Al-muqtadir Biallah. It is preserved in Mr. Ammar Omran's collection in Saudi Arabia, and it does not represent the date and minting place of the coins. It is considered one of the extremely rarest coins, and it has not been published, or published any similar one ever. It was studied in this research in descriptive-analytical method during the political & military circumstances that occurs in Tehama of Yemen in that era. Prince Mulahidh has minted this coin after his victory against Ismaili's preacher Ali bin Al-fadhl in Yemen. This Dirham in particular, and this study in general are a new addition to the field of studying Islamic coins, and the money of Yemen in the Islamic era.