Greek Orthodox Church of Jerusalem

The Greek Orthodox Church of Jerusalem (Greek: Πατριαρχεῖον Ἱεροσολύμων, Patriarcheîon Hierosolýmōn; Arabic: كنيسة الروم الأرثوذكس في القدس‎Kanisa Ar-rum Urtudoks fi al-Quds), also known as the Orthodox Patriarchate of Jerusalem, is an autocephalous Orthodox Church within the wider communion of Orthodox Christianity. Headed by the Patriarch of Jerusalem, it is regarded by Orthodox Christians as the mother church of all of Christendom. Christians believe that it was in Jerusalem that the Church was established on the day of Pentecost with the descent of the Holy Spirit on the disciples of Jesus Christ (Acts 2:1-41) and that the Gospel of Christ spread from Jerusalem. The Church celebrates its liturgy in the Byzantine rite, whose original language is Greek, and follows its own calendar of feasts, preserving the Julian calendar (that is thirteen days behind the Western (Gregorian) calendar). It is also often called "Σιωνίτις Εκκλησία" (Greek: Sionitis Ecclesia, i.e. the "Church of Zion").

The number of Orthodox Christians in the Holy Land are estimated at about 500,000 people. A majority of Church members are Palestinians and Jordanians, and there are also many Russians, Romanians, and Georgians. The Church's hierarchy is dominated by Greek clergy, which in effect excludes the Arab majority from the Church's upper ranks. This has been a point of endless contention between Greeks in the patriarchate, who are backed by the Greek government in this regard, and the Palestinians (see Arab Orthodox).

The headquarters of the Orthodox Church in Jerusalem is the Church of the Holy Sepulchre.