Article is devoted to the contidition (obligations and functions) of Prussians, who defected to the Order and church in the period of Great uprising and received the land estates for their service. The data about this category contained in acts and chronicle of Peter of Dusburg has been researched with prosopographical, typological and comparative-historical methods that allowed to form the conclusion about the condition of 245 lieges. The main part of lieges formed by persons, who were obliged to participate in the campaigns of brothers and defend lands from invasion, to build and restore fortifications and additionally to pay natural- money and natural taxes (groups 1 and 2). This situation was caused by necessity of brothers in military resource for the suppression of the uprising and further expansion in the Baltic region. In turn, persons, who were relieved from military service, performed civil duties and/or pay taxes (group 3), formed less part of lieges. Attracting Prussians on the side of Order and church was carried out by giving them rights and obligations, fixed in Culm’s charter and specified in accordance with local legal features, and also by distribution of social guarantee in the case of devastation of their estates by rebels. In this situation nobles and free tribal members perceived service to the Order and church as opportunity to improve their own condition by receiving of guarantee for property and power over other tribesmen. Keywords: Prussians, lieges, Teutonic order, Great uprising, military service, tax