We describe a simple, solid-phase chemiluminescence immunoassay for the measurement of estradiol-17 beta in extracts of peripheral venous plasma. The method has similar sensitivity, specificity, precision, and accuracy to a conventional radioimmunoassay with a tritiated antigen. An immunoglobulin G fraction od monoclonal antibodies to estradiol-6-carboyxmethyl oxime-bovine serum albumin is passively adsorbed onto the walls of polypropylene tubes. The labeled antigen is estradiol-6-carboxymethyl oxime-aminobutylethyl isoluminol. After the binding reaction (1 h at 22 degrees C), the solution is removed by aspiration (400 microliters). Sodium hydroxide (5 mol/L, 300 microliters) is added and the mixture incubated for 30 min at 37 degrees C. Luminescence is initiated by oxidation of the label with microperoxidase/hydrogen peroxide and the signal integrated for 10 s. The light yield is inversely proportional to the concentration of estradiol in the standard or sample.