Abstract: Hyperfrequency band-cut filter enabling the transmitting of a first lower frequency band and cancelling a second frequency band which is absorbed. It is constituted by a compact assembly comprising two blocks fixed to each other and forming a rectangular wave guide whose upper and lower walls are drilled with slots connected to resonant cavities at the second frequency band, hollowed out in the faces opposite to the faces of the rectangular wave guide and comprising, moreover, two plates which are screwed onto said blocks overlying said cavities.