Anti-sera against beta-subunit of human chorionic gonadotropin (HCG) was prepared from a rabbit immunized with beta-HCG purified through DEAE-Sephadex chromatography. Antibody against beta-HCG was adsorbed onto latex particles. The antibody-coated latex particles were agglutinated when they were allowed to interacted with HCG in test solutions up to the level of 2 IU/㎖. The level of HCG dose tested was sensitive enough to apply for the diagnostic tests for pregnancy. Partial purification of HCG from pregnancy urine was also investigated.