Bistrets Monastery, Medieval monastery in Vratsa Province, Bulgaria

Bistrets Monastery is a medieval religious complex in Vratsa Province featuring a church dedicated to Saint Ivan and multiple structures enclosed within stone walls. The buildings are nestled within the natural landscape of the Vrachanski Balkan mountains and organized around a main courtyard.

Founded at the end of the 11th or beginning of the 12th century, the monastery is first documented in a 1540 inscription under the Great Cave frescoes naming Dimitar sin Dubov, likely its restorer. Ecumenical Patriarch Jeremiah I of Constantinople took monastic vows here in 1545, shortly before his death. During Ottoman rule it sheltered haiduts and was repeatedly destroyed and rebuilt; in 1822 it housed Bulgaria's first copper-plate printing workshop for icons.

The monastery's name Kasinets comes from the nearby peak and locality Kasinata. Its cave frescoes, painted on a thin plaster layer over the rock, follow the 14th-century Tarnovo school; a short inscription beside them gives the year 1540 and the name Dimitar sin Dubov, likely the donor. The monastery keeps the memory of Patriarch Jeremiah I of Constantinople, who took monastic vows here in 1545 shortly before his death.

The monastery lies about 12 km northwest of Vratsa's centre, at the upper end of a steep ravine below 50 m limestone cliffs. The final approach is on foot and not a marked mountain trail; the cave chapel Postnitsata above the monastery is reached only with a ladder. Dress modestly, as this is an active place of worship.

Above the monastery, a cave called Postnitsata sits on a sheer cliff and is reached only with a ladder. Inside, 5–6 m up in a small rock niche, stands a miniature chapel with a vault of woven vine branches, whitewashed, where the figure of Christ Pantocrator can still be made out. Legend holds that Saint Ivan of Rila spent 40 days there in fasting and prayer before the rock opened for his journey to Rila.