Apparatus for filling containers with dosed quantities of powdered material, comprising a dosing wheel rotatable around a substantially horizontal axis of rotation (A), said dosing wheel comprising a discoidal body inside which it is formed a plurality of channels extending along respective radial directions from a peripheral edge of said discoidal body towards the centre of said discoidal body , each said channel having an opening at said peripheral edge which puts it in communication with the external environment; a hopper arranged above said dosing wheel and suitable for containing said powdered material; a plurality of pistons respectively slidably inserted inside said channels , each piston comprising a stem and a head integral with one end of said stem , each piston defining in said channel a calibration chamber arranged to collect a dosing quantity of said powdered material, said calibration chamber being delimited by said head of said relative piston and by an inner wall of said respective channel ; an adjustment assembly , associated with said dosing wheel , suitable for adjusting the position of each piston inside said respective channel ; characterized in that the apparatus further comprises conducting means communicating with said channels and suitable for being alternately connected to a negative pressure source and to a positive pressure source, so as to create a vacuum condition in each said calibration chamber and so as to introduce a flow of a fluid inside said calibration chamber , respectively, wherein said head of each said piston has a cross-section having a diameter (d4) which is lower than the diameter (d1) of the cross-section of an end portion of said stem , said end portion being opposite to said head , and in that each said channel has a cross-section which increases starting from said peripheral edge towards the centre of said discoidal body . a hopper arranged above said dosing wheel and suitable for containing said powdered material; a plurality of pistons respectively slidably inserted inside said channels , each piston comprising a stem and a head integral with one end of said stem , each piston defining in said channel a calibration chamber arranged to collect a dosing quantity of said powdered material, said calibration chamber being delimited by said head of said relative piston and by an inner wall of said respective channel ; an adjustment assembly , associated with said dosing wheel , suitable for adjusting the position of each piston inside said respective channel ; characterized in that the apparatus further comprises conducting means communicating with said channels and suitable for being alternately connected to a negative pressure source and to a positive pressure source, so as to create a vacuum condition in each said calibration chamber and so as to introduce a flow of a fluid inside said calibration chamber , respectively, wherein said head of each said piston has a cross-section having a diameter (d4) which is lower than the diameter (d1) of the cross-section of an end portion of said stem , said end portion being opposite to said head , and in that each said channel has a cross-section which increases starting from said peripheral edge towards the centre of said discoidal body . <EOS>