Abstract: A device for the rapid qualitative and quantitative determination of the presence of a reactive ligand in a fluid.This device comprises a first reaction zone in which there is an at least temporarily impermeable membrane designed to receive a sample of test fluid and to be associated with at least one labeled reagent; a second reaction zone which is bounded on the one hand by the said membrane and on the other by a second at least temporarily impermeable membrane comprising a solid phase containing a reference reagent; and a third reaction zone which contains means for developing the reaction.A method for the rapid qualitative and quantitative determination of the presence of a reactive ligand in a fluid.Applications to the detection of the presence, in a biological fluid, of antibodies or antigens in particular.