HCG combined with the Freund's and Ramon's adjuvants were injected into rabbits, and induced the production of anti-HCG which showed precipitation and agar gel diffusion tests. From this results, the anti-HCG serum may be used for immunological assay for pregnancy and examination in legal medicine. The anti- serum also has antihormonal preperties against the human chorionic gonadotropin activity the serum of pregnant woman, the placenta of abortion patient and the blood stain of pregnant woman.