The results of comparative studies of paddle grain conveyors of combine-harvester are presented. One of them was a conveyor which has been used so far in BIZON combine-harvester; the other one was a modified conveyor intended for combine-harvesters of higher capacity in which other dimensions of paddles and working channel were used. The research was done on a specially built research post which ensured the regulation of exploitation parameters of the conveyors under discussion. The influence of the construction of conveyors on capacity, the filling coefficient and micro- and macro-damage of the shifting grain were defined. The study proved that the modified conveyor achieved higher capacity with higher filling coefficient of working space. Thanks to better filling of the conveyor, grain underwent smaller mechanical damage.