A cupless bra, sometimes known as a shelf, open tip, open nipple or open cup bra, is a brassiere design composed of a rigid, under-wired frame along the inframammary line, that supports or lifts a woman's breasts, without enclosing the breast in a bra cup.

A cupless bra is regarded as a topless garment, as the nipples and areolae are uncovered. The garment can be regarded as erotic and seductive negligee, which can accentuate an aspect of a woman's physical attractiveness by lifting and displaying her breasts. Variants of the cupless bra are cupless corsets, miniskirts, dresses or swimsuits. There is no set terminology, but an "open nipple" refers to a garment with a cut-out circle to expose the nipples, while a shelf bra is one that merely lifts the breasts.

A cupless bra may be worn under an outer garment to provide support or lift for the breasts, while giving the impression that a woman is braless, because her nipples may be evident even through the outer garment. Open nipple and open cup bras may be used by nursing mothers for breastfeeding. (see nursing bras)