A unit (6) for checking the dosing of pharmaceutical material (M) in a capsule filling machine (1) for the production of capsules (CF) of the type with a capsule lid (C) and a capsule body (F), the machine (1) comprising a fixed structure (15) fitted with a rotary drum (2) for supporting a plurality of capsules (CF) on its edge, opening each capsule (CF) by separating the capsule lid (C) from the capsule body (F), filling the capsule body (F) with a dose of material (M), then closing the capsule body (F) again with the relative capsule lid (C); the rotary drum (2) having a tank (5) containing the pharmaceutical material (M) and supporting a plurality of doser elements (3), each comprising at least one piston (8) sliding inside a hollow cylinder (4) to pick up and compress a dose (DS) of material (M) from the tank (5) and discharge it into a capsule body (F) of a capsule (CF). The unit (6) comprises sensor means (9) attached to each piston (8) for detecting a piston (8) thrust value (V; V1) on the dose (DS) and transmitter means (10) connected to the sensor means (9) for transmitting the value (V; V1) to a receiver element (11; 41) by the telemetric transmission of a relative signal (S; S1), said receiver element (11; 41) being fixed on the machine (1) in at least one zone (P1; P2) of the fixed structure (15). Power supply means (12, 14a) are also provided for cyclically activating the sensor means (9) and the transmitter means (10) during drum (2) rotation.