Abstract: Immunoassay for Poisons is based on Clssical immunochemical procedures and utilizes an antigen-antibody reaction as an analytic means. It can determine the poisons contained in the blood or urine Sample quantitatively and directly No isolation is necessary, Thus this procedure can be performed easily and rapidly, and the results obtained are sensitive. For instance, the sensitivity of radioimmunoassay is 10, 000～10, 000, 000 times as high as that of the triditional method, up to ng(10~(-12)). The main adventage of this method is that it can be used as a Screening test, especrally the negative exclusive tests. This paper presents morphine radioimmunoassay and enzyme inhibition immunoassay, including the preparation of antigen and antibody, labelling of antigen and quantitative Procedures, etc.