Apparatus for filling containers with dosed quantities of powdered material, comprising a dosing wheel rotatable around a substantially horizontal axis of rotation, 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 which is lower than the diameter 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 which is lower than the diameter 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.