In this paper a method is represented which is used for the quantitative estimation of receptor binding for progesterone and oestrogens and its preliminary use is proved for relevant target tissue from cattle and swine. By means of saturation analysis and under use of tritium-labelled steroids a comprehensive characterization of the receptor assays is possible. The characterization encloses the testing of optimal incubation time and -temperature, the representation of connections between specific receptor binding and protein content of the cytosol, the examination of the hormone specifity of the receptor binding, the analysis of the storage ability of the cylosol as well as of the precision of the receptor assays.