Abstract: The present invention provides a process for the determination of an antibody in human body fluids according to the immunoassay principle in which a sample containing the antibody to be determined is incubated with at least two different receptors R.sub.1 and R.sub.2, of which one receptor R.sub.1 carries an antigenic determinant specific for the antibody to be determined and one receptor R.sub.2 carries a label to form bound and unbound label, the part which contains the bound label is separated from the part which contains the unbound label and the label is measured in one of the two parts, wherein, for the control, instead of the sample, there is used a standard solution which contains a conjugate of a bindable non-human antibody or a Fab or F(ab').sub.2 fragment thereof which non-human component binds with a receptor R.sub.s which also binds to the antibody to be determined, and a human immunoglobulin or the Fc part thereof.