Abu Tahir Firuzshah (Persian: ابو طاهر فیروز شاه), better known by his laqab of Diya' al-Dawla, was the Buyid ruler of Basra during the 980s.
Abu Tahir Firuzshah was the son of Adud al-Dawla and a daughter of Manadhar, who was a Justanid king.
This invasion distracted Samsam al-Dawla and gave Abu Tahir Firuzshah the ability to set up his own independent rule in Basra, where he took the title of Diya' al-Dawla.
Nevertheless, after a few years Sharaf al-Dawla invaded and occupied Basra and Khuzestan, causing the two princes to flee to Fakhr al-Dawla's territory.
Neither of the two brothers managed to found any lasting line; consequently their role in Buyid politics was short.