The PSA Screen Test utilizes two site sandwich immunoassay technology and specific antibodies to PSA for the semi-qualitative detection of PSA concentration in serum. PSA specific antibodies are pre-coated onto membrane as a capture reagent on the test band region. During the assay the specimen reacts with anti-PSA gold-conjugate. The mixture then moves laterally on the membrane chromatographically to the test region with immobilized anti-PSA on the membrane. If PSA is present in the specimen, a color band is formed in the test region. PSA internal standard is pre-coated on the reference band region indicates equal 4ng/mL of PSA concentration. And followed by a built-in system control with anti-PSA antibody on the control band region. Both of the color bands in the reference region and control region will always appear regardless the presence of PSA in serum sample.