Abstract: A valve for the treatment of hydrocephalus of the type including a membrane provided with an aperture and demarcating within a housing an upstream chamber and a downstream chamber. A rod of variable cross section attached to a stopper penetrates into the aperture. According to the invention, the housing includes three parts, a first body, a second body and a base cap. The first body and second body are assembled so as to squeeze the periphery of the membrane. The first body, the stopper and a first face of the membrane form one of the chambers, and the second body, the base cap and the other face of the membrane form the other chamber.