Multiple epitope fusion proteins and immunoassays using the same are disclosed. The multiple epitope fusion proteins are encompassed by the general structural formula (A).sub.x-(B).sub.y-C.sub.2 which represents a linear amino acid sequence, wherein B is an amino acid sequence of an epitope or cluster of epitopes and each B contains at least five and not more than 1,000 amino acids, y is an integer of 2 or more, A and C are each independently an amino acid sequence of an epitope or cluster of epitopes not adjacent to B in nature and x and z are each independently an integer of 0 or more wherein at least one of x and z is 1 or more.