The aim of the article is primarily to present the missionaries working in the Gniezno seminary. Takeover of the management of the Gniezno seminary by the missionaries of St. Vincent de Paul in 1718 opened a new chapter in its history and in the formation of priests of the archdiocese. Until the third partition of the Republic of Poland in 1795, several dozen monks worked in this institution. They were responsible both for the intellectual and spiritual formation of the students, as well as for providing them with the material basis of existence. The knowledge and personal example of life passed on, as well as practical pastoral activities, allowed the preparation of several hundred pastors for the needs of the vast Archdiocese of Gniezno in the years 1718-1795. The origins, beginnings and material basis of missionaries' activities constitute an important context of formation work in Gniezno. They were presented in the first part of the article. Then, the staff at the seminar was discussed, divided into positions held.