The dalmatic is a long, wide-sleeved tunic, which serves as a liturgical vestment in the Catholic, Lutheran, Anglican, United Methodist, and some other churches. When used, it is the proper vestment of a deacon at Mass, Holy Communion or other services such as Baptism or Marriage held in the context of a Eucharistic service. Although infrequent, it may also be worn by bishops above the alb and below the chasuble, and is then referred to as pontifical dalmatic.

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Like the chasuble worn by priests and bishops, it is an outer vestment and is supposed to match the liturgical colour of the day. The dalmatic is often made of the same material and decoration as a chasuble, so as to form a matching pair. Traditional Solemn Mass vestment sets include matching chasuble, dalmatic, and tunicle.

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A dalmatic is also worn by the British monarch during the Coronation service.

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The dalmatic is a robe with wide sleeves; it reaches to at least the knees or lower. In 18th-century vestment fashion, it is customary to slit the under side of the sleeves so that the dalmatic becomes a mantle like a scapular with an opening for the head and two square pieces of the material falling from the shoulder over the upper arm. Modern dalmatics tend to be longer and have closed sleeves, with the sides being open below the sleeve. The distinctive ornamentation of the vestment consists of two vertical stripes running from the shoulder to the hem; according to Roman usage these stripes are narrow and sometimes united at the bottom by two narrow cross-stripes. Outside of Rome the vertical stripes are quite broad and the cross-piece is on the upper part of the garment. At a Pontifical High Mass, a dalmatic (usually made of lighter material) is worn by the bishop under the chasuble. At solemn papal liturgical occasions the Pope is assisted by two cardinal-deacons vested in a dalmatic and wearing a mitra simplex (simple white mitre).