Alpha-fetoprotein (AFP) is a glycoprotein with a molecular weight of approximately 70 KD(1). AFP is normally produced during fetal and neonatal development by the liver, yolk sac, and in small concentrations by the gastrointestinal tract (2). After birth, serum AFP concentrations decrease rapidly, and by the second year of life and thereafter only trace amounts are normally detected in serum. Elevation of serum AFP to abnormally high values occurs in several malignant diseases (4-7), most notably nonseminomatous testicular cancer and primary hepatocelluar carcinoma. In the case of nonseminomatous testicular cancer, a direct relationship has been observed between the incidence of elevated AFP levels and the stage of disease (8-9). Elevated AFP levels have also been observed in patients diagnosed with seminoma with nonseminomatous elements, but not in patients with pure seminoma (6,8,10-11). In addition, elevated serum AFP concentrations have been measured in patients with other noncancerous diseases, including ataxia telangiectasia, hereditary tyrosinemia, neonatal hyperbilirubinemia, acute viral hepatitis, chronic active hepatitis and cirrhosis (12-15). Elevated serum AFP concentrations are also observed in pregnant women (16-17). Therefore, AFP measurements are not recommended for use as a screening procedure to detect the presence of cancer in the general population