Nestinarstvo (Bulgarian: нестинарство) is a fire ritual originally performed in several Bulgarian - and Greek - speaking villages in the Strandzha Mountains close to the Black Sea coast in the very southeast of Bulgaria. It involves a barefoot dance on smouldering embers (жарава, zharava) performed by nestinari (нестинари). It is usually performed on the square of the village in front of the whole population on the day of ‘’Sts. Constantine and Helen’’ or the day of the village's patron saint.
The ritual is a unique mixture of Eastern Orthodox beliefs and older pagan traditions from the Strandzha Mountains.
The rite of fire dancing is one of the oldest Bulgarian folk traditions and was once practiced by ancient Thracians living near The White Sea. It is performed today in only a few mountain villages in the Strandzha region, such as Bulgari, Kosti, and Brodilovo.

In 2009, the ritual was included as a UNESCO World Heritage legacy of non-material culture.
According to a number of scholars, the ritual was performed by a Thracian cult that worshipped the sun.
The dance is performed barefoot on live coals, and this unique rite is now connected with groups whose patron saints are Constantine and Elena. While fire dancing is connected with celebrations that are observed year round, the day most closely connected with the practice is June 3 (according to the old calendar), since that is the day these two saints are honored.
Traditionally, the right to perform the ritual would be hereditary and the head nestinar may be succeeded only by his or her son or daughter, and only when he or she is too old or ill to continue performing it. The head nestinar's house is sacred, because it houses the stolnina (столнина) – a small chapel where icons of several saints are arranged, as well as a sacred drum used specifically for the ritual and believed to cure the drummer if he is ill.
During the day of June 3, the icons that are sacred to the fire dancers are “clothed” – a bright red cloth is placed over them that has old silver coins sewn on it and is colorfully decorated. The whole village then takes part in a procession to transport the icons to the holy spring of Saint Constantine, there the handles used to carry the icons are washed.

The preparation of the fire for the dance starts before noon. The fire must be laid in a symmetrical circle, so that those in attendance can all observe the rite. Before evening, the fire dancers and a representative of the church go to a chapel that is dedicated to Saints Constantine and Elena, where they breathe deeply of the incense and pray before the icons. Later, after it gets dark, the whole village gathers at the chapel, including musicians – a gayda (Bulgarian goatskin bagpipe) player and a drummer.
The musicians play three special melodies – the first as the celebrants make their way from the chapel to the fire, the second when the dancers approach the coals, and the third to accompany the Kostadin Horo (a group dance). Then there is a second ritual procession circling the fire, and the culmination of the ceremony begins.

In a trance, the fire dancers move into the circle of celebrants, and after the first dancer traverses the coals in the pattern of a cross, the other dancers enter the fiery circle. The movements that the dancers make on the burning coals are intricate and orderly, but nevertheless their bare feet are not burned. When the ritual dance concludes, all of those present again perform the Kostadin Horo, as a kind of prayer for good health.
With swan-like movements the first of the Nestinari walks over the fire. He carries the icon of Saint Konstantin and is rapidly followed by a woman carrying the icon of Saint Elena. Everybody shouts and claps their hands. Then a third Nestinari goes accros. At a very relaxed pace this time and actually lingering and going back and forth somewhere near the middle. This goes on for maybe ten minutes. Every time before the Nestinari cross the fire they pause their rhythmic movements for a few heartbeats. They seem to gather some sort of mystic energy that allows them to walk on the burning coals unharmed.

At present, the tradition of fire dancing is observed most faithfully in the village of Bulgari in the Strandzha, and every year on June 3 visitors come to the village from all over the world to observe the rite.