Human Chorionic Gonadotropin (hCG) is a 40 kD glycoprotein hormone secreted by the placenta. The serum hCG rises in early pregnancy to concentrations of 50,000-150,000 mIU/ml between the 8th and 12th weeks of gestation and decline to 20,000 mIU/ml by the 18th week where they remain for the duration of the pregnancy. The increased level of hCG in non-pregnant women or men suggest neoplsia. Thus hCG measurement is useful for the recognition and monitoring of chorionic tumors and as a tumor marker for other malignancies that produce hCG ectopically. These include testicular, pancreatic and bronchogenic pulmonary cancers. BioVision hCG ELISA Kit is a direct solid phase sandwich ELISA method. The samples and diluted anti-hCG-HRP conjugate are added to the wells coated with Mab to beta subunit. hCG in the serum binds to anti-hCG MAb on the well and the anti-hCG second antibody then binds to hCG. Unbound protein and HRP conjugate are washed off by wash buffer. Upon the addition of the substrate, the intensity of color is proportional to the concentration of hCG in the samples. A standard curve is prepared relating color intensity to the concentration of the hCG. The sensitivity of this ELISA test is 0.5mIU/ml.