Orthros (Greek: ὄρθρος, meaning "early dawn" or "daybreak") or útrenya (Slavonic ѹ́тренѧ) in the Byzantine Rite of the Eastern Orthodox Church and the Eastern Catholic Churches, is the last of the four night offices (church services), the other three being vespers, compline, and midnight office. Traditionally, in monasteries it is held daily so as to end immediately following sunrise, in contrast to parishes where it is held only on Sundays and feast days. It is often called matins after the office it most nearly corresponds to in Western Christian churches.
Orthros is the longest and most complex of the daily cycle of services. It is normally held in the early morning, often — always in monasteries — preceded by the midnight office, and usually followed by the First Hour. On great feasts it is held as part of an all-night vigil commencing the evening before, combined with an augmented great vespers and the first hour. In the Russian tradition, an all-night vigil is celebrated every Saturday evening, typically abridged, however, in spite of its name, to as short as two hours. In the Greek parish tradition, orthros is typically held immediately prior to the beginning of the divine liturgy on Sunday and feast day mornings.