The evaluation of the migration inhibition test with thyroid membrane antigen was carried out in 20 patients with Graves' disease, 13 patients with neutral nodular goiter and 13 healthy subjects. A significant inhibition of migration by thyroid antigen as compared to the control group was demonstrated only in the patients with Graves' disease (the value of the migration index was 0.57 +/- 0.07). The respective value was 0.79 +/- 0.16 in patients with nodular goiter and 0.85 +/- 0.11 in healthy subjects. The results obtained indicate the practical value of the migration inhibition test in diagnosing the thyroid diseases having an autoimmune background.