Vietnamese Yếm refers to an ancient Vietnamese bodice used primarily as an undergarment that was once worn by Vietnamese women across all classes. There exists a modern variant called "áo yếm", but the historical garment was simply called "yếm". It was most usually worn underneath a blouse or overcoat, for modesty's sake.

It is a simple garment with many variations from its basic form, which is a simple, usually diamond or square-cut piece of cloth draped over a woman's chest with strings to tie at the neck and back.

Yếm is similar to a garment called dù dōu (Chinese: 肚兜) that existed in ancient China. The origin of the yếm is still unknown to many historians and scholars. The yếm has been worn by northern Vietnamese women traditionally. Unlike other Vietnamese clothing that helped to segregate the classes, yếm were worn as an undergarment by Vietnamese women of all walks of life, from peasant women toiling in the fields to imperial consorts.

It is an integral part of the Áo tứ thân costume, which it is often worn underneath.