a mortgage deed, also known as a mortgage agreement, is a document where a borrower of money grants the lender of that money conditional ownership in a property as a security interest against the loan until the loan is paid in full. mortgage deeds are most commonly used to secure a loan taken out by the borrower to purchase a piece of property or home. the purchase of a property or home is often a big investment that involves a substantial amount of money. a mortgage deed allows them to take possession and sell the property if the borrower stops making loan payments. a mortgage deed is used specifically to put up a piece of real property, like land or a home, as security. a mortgage deed and a deed of trust both create a lien on a property to secure repayment of a loan.