This study was performed in order to explore the immunologic relationship between the skin lesions induced by the human serum and the lymphatic organs. For these purposes, the authors induced the dermatitis in the rabbits by the injections of pooled human serum with Freunds complete adjuvant into the skin, and administered prednisolone and azathioprine as immunosuppressive drugs to the rabbits. Immunologic asmy was performed by the measurement of the plasma ceIls and immunogobulin-bearing B lymphocytes in lymph node and spleen. The results were as follows: 1. By the injections of human serum pyroninophilic cells and immunoglobulining B lymphocytes in lymph node and spleen were increased. 2. By the administrations of prednisolone and azathioprine, pyroninophilic cells and immunoglobulin-bearing B lymphocytes in lymph node and spleen were all decre RSCd.