The term Gerontism is a term that referred to a administration system of the Ecumenical Patriarchate, consisting of senior hierarchs, that was established in the middle of the eighteenth century during the first period of the tenure of Patriarch Samuel I Chatzeres as patriarch.
In 1767, the metropolitans of the dioceses that were near Constantinople established themselves as an ecclesiastical oligarchy and became responsible for the administration of the patriarchate in cooperation with the patriarch. These metropolitans, called 'Gerontes' - elders, were from the dioceses that were near Constantinople and who had the possibility of maintaining a permanent presence in the capital. Initially, the members of the group included the hierarchs of Heraclea, Chalcedon, Nicomedia, Cyzicus, and Nicaea. Later the metropolitans of Derkoi, Ephesus, and Caesarea were added.
Gerontism provided improved administrative competence within the patriarchate, as the gerontes' lengthy presence and experience in Constantinople provided experience in the management of eventual crises. However, in reality the Elders would often impose on the patriarch their own decisions and could even cause his dethronement. Also, the system was a source of financial and other abuse, including undermining the patriarch's status and autonomy.
The system of gerontism was abolished after the adoption of the "General" or "National Regulations" by the National Assembly of the Orthodox millet that was held in Constantinople from 1858 to 1860 in accordance with the imperial decree [[w:Hatt-ı_Hümayun|Hatt-ı Hümayun] of 1856 that among other provisions provided for the reorganization of the ethnic-religious communities of the Ottoman Empire.