The Defence of the Seven Sacraments (Latin: Assertio Septem Sacramentorum) is a theological treatise published in 1521, written by King Henry VIII of England, allegedly with the assistance of Sir Thomas More.

[4] By June of that year, he had shown it to Thomas Wolsey, but it remained private until three years later when the earlier manuscript became the first two chapters of the Assertio, the rest consisting of new material relating to Luther's De Captivitate Babylonica.

Author J. J. Scarisbrick describes the work as "one of the most successful pieces of Catholic polemics produced by the first generation of anti-Protestant writers".

The treatise was dedicated to Pope Leo X, who rewarded Henry with the title Fidei Defensor (Defender of the Faith) in October 1521 (a title revoked following the king's break with the Catholic Church in the 1530s,[6] but re-awarded to his heir by the English Parliament).

[8] The British Library still has King Henry's personal copy of Marko Marulić's Evangelistiarium, a book that was read in English and much admired by Thomas More.