Abstract: What is disclosed is a method for the immunological determination of an immuno-complex, comprising an antigen and an antibody, in a liquid containing said immuno-complex, which method comprises(a) incubating said liquid containing said immumo-complex with a first reagent bound to a carrier, said first reagent being specific for an antigenic determinant of the antigen in said immuno-complex and being present in an amount sufficient to fix said immuno-complex;(b) separating the carrier from said liquid containing said immuno-complex and incubating it in a solution of a second reagent, said second reagent being specific for an antigenic determinant of the antibody in said immuno-complex and being present in an amount sufficient to fix said immuno-complex; and(c) separating the carrier from said solution of the second reagent and determining the amount of bound or unbound second reagent.