Method to determine a specific substance capable of binding

To determine a specific binding substance by incubation of the sample solution with at least three receptors R₁, R₂ and R₃, of which R₁ and R₂ are bondable together and R₃ is specifically bindable with the substance to be determined and measuring the agglutination occurring in the reaction, is used as Receptor R₁ is a conjugate of a partner of a specific binding pair P and a substance S corresponding to the substance to be determined or a derivative thereof and having at least one epitope of the substance to be determined, as R₂ a receptor having at least two binding sites for P. and as R₃ a receptor having at least two binding sites, of which at least one binds specifically with an epitope of the substance to be determined or of S.