The Diet of Speyer or the Diet of Spires (sometimes referred to as Speyer V) was a diet of the Holy Roman Empire in 1570 in the Imperial City of Speyer (alos known as Spires, in present-day Germany). The diet condemned the results of the Diet of Speyer of 1526 and prohibited future reformation. It resulted in the Protestation at Speyer.
The Diet decided to allow printing only in free imperial cities, residences and university towns.
The Diet also decided to return part of the land confiscated from Elector John Frederick II of Saxony to his children John Casimir received the Coburg area and John Ernest received the Eisenach area.
The Diet also agreed to the Treaty of Speyer (1570) in which King John II Sigismund Zápolya abdicated as King of Hungary in favor of Emperor Maximilian II. John became Prince of Transylvania.