A chemiluminescence immunoassay for the quantitative determination of progesterone in serum and plasma. The DRG Progesterone CLIA Kit is a chemiluminescence immunoassay (CLIA), based on the principle of competitive binding. The microtiter wells are coated with a polyclonal antibody directed towards an antigenic site on the Progesterone molecule. Endogenous Progesterone of a sample competes with a Progesterone horseradish peroxidase conjugate for binding to the coated antibody. After incubation the unbound conjugate is washed off. The amount of bound peroxidase conjugate is reverse proportional to the concentration of Progesterone in the sample. After addition of the substrate solution, the intensity of emitted light is reverse proportional to the concentration of Progesterone in the sample.