August 17 - Eastern Orthodox liturgical calendar - August 19

All fixed commemorations below are observed on August 31 by Eastern Orthodox Churches on the Old Calendar.^{[note 1]}

For August 18, Orthodox Churches on the Old Calendar commemorate the Saints listed on August 5.

• Afterfeast of the Dormition.^{[1][note 2]}

• Martyrs Florus and Laurus of Illyria, twin brothers who worked as stonemasons (2nd century)^{[1][3][4][5][note 3][note 4]}
• The Holy Host of Paupers (300 martyrs), brought together by Saints Florus and Laurus, who smashed the statues of the pagan gods and were martyred by fire.^{[7][8][note 5]}
• Martyrs Hermes, Serapion, Polyaenus of Rome (2nd century)^{[1][5][9][10][note 6]}
• Hieromartyr Emilian, Bishop of Trebia in Umbria, and lay martyrs Hilarion, Dionysius, Hermippus, and about 1,000 others, in Italy (c. 300)^{[1][11][12][note 7]}
• Venerable Barnabas and his nephew Sophronius, founders of Mount Mela Monastery (Panagia Soumela), near Trebizond (412)^{[1][5][15][16]}
• Venerable Christopher of Trebizond, Abbot of Mount Mela Monastery (Panagia Soumela) (668)^{[1][5][15][17]}
• Saints John (674)^[18] and George (683),^[19] Patriarchs of Constantinople.^[1][5][20]
• Martyr Juliana near Strobilos in Lycia.^{[1][5][6][21][note 8]}
• Martyr Leo, drowned off the coast of Myra in Lycia.^{[1][5][6][22][note 9]}
• The 4 Venerable Ascetics, reposed in peace.^[23][24]
• Saint Macarius, Abbot of the Pelekete monastery near Prusa, Bithynia (840)^[1][25][26] (see also: April 1)
• Venerable John of Rila, founder and Abbot of Rila Monastery, Bulgaria (946)^[1][25][27] (see also: October 19)

• Saint Agapitus of Palestrina, a fifteen-year-old who bravely confessed Christ and was martyred in Palestrina near Rome (c. 274)^{[28][note 10]}
• Martyrs John and Crispus, priests in Rome who devoted themselves to recovering and burying the bodies of the martyrs, for which they also suffered martyrdom.^{[28][note 11]}
• Saint Firminus of Metz, Greek or Italian by origin, he was Bishop of Metz in France for eight years, Confessor (496)^[6][28]
• Saint Daig Maccairill (Daig, Dagaeus, Daganus), disciple of St Finian, he founded a monastery at Inis Cain Dega (Inniskeen), and was both abbot and bishop (586)^[28]
• Saint Milo, a monk together with his father at Fontenelle Abbey in France, and later a hermit (c. 740)^[28]
• Saint Inan (Evan),a hermit in Ayrshire in Scotland, where churches are dedicated to him (9th century)^[28]

• Saint Christodoulus the Philosopher, called "the Ossetian," of Georgia (12th century)^[1][25][29]
• Venerable Sophronius of St. Anne's skete on Mount Athos (18th century)^{[1][5][30][31]}
• New Monk-martyr Demetrius the Vlach, of Samarina (Pindos), at Ioannina (1808)^[1][5] (see also: August 17)

• Uncovering of the Relics of Venerable Arsenios the New of Paros (1877)^[5][33][34]
• Repose of Schemamonk Nicholas "the Turk," of Optina Skete (1893)^[1]

• A15th-century Novgorod icon of Sts. Florus and Laurus.
• Sts. Florus and Laurus.
• Hieromartyr Emilian, Bishop of Trebia in Umbria.
• Mount Mela Monastery (Panagia Soumela), founded by Barnabas and Sophronius, and later Christopher of Trebizond.
• St. John of Rila, fresco from Rila monastery, Bulgaria.