The ultrastructural organization of erythrocytes, thrombocytes and white cells (pseudoeosinophils, eosinophils, basophils, lymphocytes, monocytes) of the peripheral blood was studied in the pigeon Columba livia. The specific granules of eosinophils do not contain crystalloid structures characteristic of eosinophilic granules of certain respresentatives of fishes and mammals. Specific basophilic granules are of a large size and have homogeneous osmophilic matrix. The ultrastructure of agranulocytes (lymphocytes and monocytes) have no substantial distinctions from the similar cells of other representatives of vertebrates.