Seret or Sereter Hasidim were a group of Hasidic Jews that existed in the town of Siret (Seret) and the surrounding area in Bukovina (currently split between Romania and Ukraine) during the late nineteenth century until World War II.
They were headed by their Rebbe ("Grand Rabbi") whose family name was Rubin and was a scion of the Hasidic dynasties of the Kosov, Ropshitz and Belz. In practice the Seret Hasidic group was a branch of the Kosov dynasty.
The best known Rebbe of Kosov (forerunner of the Vizhnitz Dynasty), Rabbi Chaim Hager died in 1854 in Kosov (at that time in East Galicia in Eastern Europe) and left three sons, each of whom had a great number of followers (Hasidim).
The followers of the Hager family, whose numbers in Bukovina were great and who were important, tried to persuade one of the brothers, the second oldest, Rabbi Yosef Alter Hager, to move his permanent residence to Radovitz (Radauti). They wanted thereby to increase the number of visitors to the town, because the followers of the rabbi were accustomed to come from near and far for all holidays and even at other times to make pilgrimages to him.
They were successful, and in 1856 he was received in Radovitz with great ceremony by the whole population.
Reb Yosef Alter was married to Leah, the granddaughter of Reb Moshe Tzvi of Savran.
Reb Yosef Alter did a lot to stimulate the Jewish community and he worked hand in hand with the community's Rabbi Schapira to increase the spirituality of the well-to-do. It is true that he sometimes had conflicts regarding the observance of the Sabbath, because as market day was Friday, some of them continued to work after the beginning of the Sabbath–something on Friday eve, that had much upset his father, Rabbi Chaim Hager, too.