Abstract: This coat-antibody-count PAP IRMA is a solid-phase immunoradiometric assay based on two strains of monoclonal antibodies, designed for the quantitative measurement of prostatic acid phosphatase(PAP) in serum. The minimal detectable concentration is 0. 1 μg/L. The intra and inter coefficients of variation are 8. 8%-9. 6% and 7. 7%-12. 3%, respectively. The recovery is 96. 3%-105. 0% and the range of detection is 2. 5 - 200. 0μg/L.