Foot valve (7) for drip chambers (1) of medical infusion or transfusion apparatuses, having an annular valve seat (15) with which a float obturator (11) axially displaceable between a position for closing and a position for opening the valve seat (15) cooperates. The foot valve (7) comprises a containment cage bush (8) having an elastically deformable lateral wall (9) within which the float obturator (11) floats in a guided fashion, and the lateral wall (9) of the containment bush (8) and the float (11) have respective mutually facing surfaces (14, 18) and configured such that a radial deformation of the containment bush (8) applies an axial thrust to the float obturator (11) in the direction of moving it apart from the annular valve seat (15).
