The importance of eggs as a source of specific antibodies is well recognized. Egg yolk contains 8-20 mg immunoglobulins (IgY) per milliliter. However, the major problem in separating IgY is to remove the high concentrations of lipids in egg yolk. We first used water dilution method to get the supernatant containing IgY, then purified the antibody by caprylic acid-ammonium sulfate method, and obtained specific antibody with satisfactory purity and activity. By comparison of these several methods, each has its advantages, one can be chosen to purify IgY according to practical need. The purified Igy produced by the immunized chickens can stain the human peripheral blood mononuclear cell effectively when labeled with fluorescent FITC. (c) 2005 Elsevier Inc. All rights reserved.