Phrabat Somdet Phra Ratsadathirat (1529–1534) was the king of Ayutthaya from 1533 to 1534 - only for 5 months. Prince Ratsadathirat was the son of Borommaracha IV who died suddenly in 1533 from an epidemic. Prince Ratsadathirat, aged 5, succeeded his father as the king of Ayutthaya. Due to his minority, his government was dominated by a number of regents including the Samuha Nayok and the Samuha Kalahom.

In 1534, his uncle Prince Chairacha

Chairacha

Phrabat Somdet Phra Chairachathirat reigned 1534–1546 as King of the Ayutthaya kingdom of Siam. His reign was remarkable for the influx of Portuguese traders, mercenaries, and early Modern warfare technology.-Uparaja:...

 who was the Uparaj at Pitsanulok staged a coup and executed Ratsdadathirat and then assumed the throne of Ayutthaya.