The first groups started arriving there on Monday and the last ones will depart on Thursday, before the start of the Sabbath.
The prayers, lasting two to three hours, are recited at Weisblum's tomb.
Hasidic Jews believe that a person's soul returns to the place of his or her burial on the anniversary of their death. They visit Weisblum's grave in Leżajsk to ask his spirit to help them with important life issues, such as health and prosperity in business and family.
All requests are written down on small pieces of paper, which are then placed on the grave. After the prayers, which are accompanied by traditional dances and the singing of psalms, Jews eat a kosher meal consisting of beef, fish, eggs, fruit and vegetables.
Weisblum was one of the founders of the Hasidic movement, whose aim was to revive Judaism in the 18th century. He gained a reputation as a healer of souls and bodies and wrote a treatise called Noam Elimelech, published in 1787.
Before World War II, Leżajsk had a sizeable Jewish population and was among the most important centres of the Hasidic movement in Poland. The tradition of the annual prayers at Weisblum's tomb was revived in the 1970s.
For Hasidic Jews, Leżajsk, a town of some 14,000, is one of the most sacred places in the world. It attracts many Jewish groups to observe various Jewish holidays as well as during private pilgrimages and tours of Poland.
(mk/gs)