A grinding chamber (1) of a grinding device for vegetal products suitable to form beverages, particularly roasted coffee beans, comprising, in its interior, a pair of grinders (9, 11) axially overlapping each other, one (9) of which is rotatable with respect to the other (11) which is kept stationary, a grinder support (7) at least for said rotatable grinder (9), a motor member (5) connected to said grinder support (7) for setting said rotatable grinder (9) in rotation. The grinding chamber (1) is formed by a first bottom wall (3), perpendicular to the axis of rotation (X-X) of the rotatable grinder, adjacent and below the support (7) thereof, as well as at least a second cylindrical wall (2), connected axially to said first wall at the peripheral boundary thereof. Said grinding chamber (1) is also provided with a first opening (15) for introducing therein the beans of the product to be ground and with a second opening (17) for discharging the ground product. Labyrinth means (18, 21, 22) are provided between
