A fixing system for a seat, in particular an aircraft seat, comprising a base having attachment portions which are adapted to be set in an active position for attachment of the seat, by an operating lever which is movable to an active position for blocking the attachment portions, and which comprises a catch for locking the lever in the active position which is carried by the lever or the base and is adapted to cooperate with holding portions in order to lock the lever in the active position, the catch being movably mounted against the urging of resilient portions in order to allow the catch to pass over the holding portions and engage in the locking position, and to be disengaged under the action of rotary operating portions.