A diaphragm (M) pump comprising a body (1) comprises a suction connection (2) and a discharge connection (3), a suction valve (4) and a discharge valve (5); a control chamber (6) in which the diaphragm (M) is disposed, and a working chamber (10) located on the side of the diaphragm opposite the control chamber; a control pipe (8) suitable for linking the control chamber (6) to a control connection (9) of the body, said control pipe making it possible to alternately apply a vacuum and a pressure on the diaphragm; the body (1) comprises a housing (11) oriented transversely relative to the control pipe (8), said housing being open towards the outside at one end, and closed at the other end by a bottom (13) comprising a suction opening (14) and a discharge opening (15), the diaphragm (M) being positioned close to the bottom, and being held by a cap (16) engaged in the housing, said cap having a recess forming the control chamber (6), linked to a passage (7) that opens on the lateral surface of the sleeve to establish communication with the control pipe (8), the cap (16, 16a) being held in place in the housing by a ring (17) linked with the pump body.