Moni Kleiston, Orthodox monastery in Fyli Municipality, Greece

Moni Kleiston is a monastery dedicated to the Dormition of the Virgin, built at about 600 m on the southwestern foothills of Mount Parnitha in Attica, near the ancient fortress of Phyle and roughly 3 km from Chasia. Its site, enclosed by mountains, looks south over the Thriasian plain, the Attica basin and the Saronic islands.

Founded around the beginning of the 11th century, the monastery was at times a male and at times a female community. In 1930 it was a male monastery; in 1933 Archbishop of Athens Chrysostomos Papadopoulos re-established it as a female one (Presidential Decree of 25/7/1933, Government Gazette 275/1933). Seven nuns lived there in 1951 and eight in the 2001 census. Since 2010 it belongs to the Metropolis of Ilion, Acharnes and Petroupoli, having previously been under the former Metropolis of Attica.

The monastery is dedicated to the Dormition of the Virgin Mary. Its name, Kleiston, comes from the site being enclosed by mountains. It was re-established as a women's monastery in 1933 by Archbishop Chrysostomos Papadopoulos; by 2001 it housed eight nuns.

The monastery sits about 3 km from Chasia on the southwestern foothills of Mount Parnitha, at roughly 600 m altitude near the ancient fortress of Phyle. There is no direct public transport, so a taxi or rented car is the usual way; the drive from Athens takes about 45 minutes. Visitors can combine the trip with a walk in the surrounding mountains or a visit to the fortress.

The name Kleiston comes from the monastery's position, walled in by mountains. Founded around the early 11th century, it was a male house in 1930 and was re-established as a female convent in 1933 by Archbishop Chrysostomos Papadopoulos of Athens. Seven nuns lived there in 1951 and eight were counted in 2001.