Estimation of the degree of leukocyte migration inhibition in the oral cavity, following exposure to allergen solution, is a test widely used to assess a subject's allergy to drugs. To simplify this test and make it more effective, the authors suggest placing the samples in plate wells and drying them there; optically transparent polystyrene plates for enzyme immunoassay are employed. Effective adsorption of the cells on the carrier and the possibility of analyzing the samples with the help of multiple magnification permit a reliable detection of the migration inhibition. The method was tried in examinations of workers engaged in the manufacture of an x-ray contrast agent triambrin. Reduced migration levels were detected in 8 of the 12 examinees.