Alpha-fetoprotein (AFP) is a glycoprotein with a molecular mass of 65,000 Daltons. It is normally produced in large amounts by liver, the visceral endoderm of foetus. Alpha-fetoprotein level increases progressively and reaches a peak at the 30th week in the maternal serum. Thereafter, it decreases gradually and reduces to trace amount with a couple of years after birth. Human AFP gene is located at the chromosomal location 4q25. The expression of AFP is regulated by a large promoter P1 and three distant enhancers. AFP expression abnormality is a relatively common genetic disorder that affects intellectual development and causes other health problems. Increased AFP expression is observed in adults that developed metastasis of liver and other organs. AFP is thought to be a foetal form of serum albumin and exists in monomeric, dimeric and trimeric forms. It binds to copper, nickel, fatty acids and bilirubin. The exact function of human AFP is still under investigation. Several hypotheses have been proposed for the physiological function: regulation of cell growth, sexual differentiation, transportation of metals and other substances, interaction with cytoplasmic chaperone proteins, and protecting foetus against the maternal immunity. To cover the very large range of concentration associated with the great variety of processes, the current immunoassay is a simple tool for the detection of AFP in the range 0 – 400ng/ml.