Antibodies are immunoglobulins produced by B cells when antigens such as allergens or pathogens invade an animal's body. The antibodies remove and inactivate antigens. Antibodies are distributed in internal body and mucosal membrane to protect living animals, but they are excellent proteins that can exert their functions, "antigen-antibody reactions," even when removed from the body. For that reason, antibodies are being put to practical use in diagnostic kits for conditions such as pregnancy and influenza infection, and as anticancer drugs targeting specific tumor markers. The result has been an increasing use of antibodies for research, diagnosis, and therapeutic purposes. Unfortunately, antibodies from experimental mammals such as mice, rats, and rabbits, are not suited to industrial use because of their high production cost. Moreover, handling of these antibodies is difficult due to their vulnerability to heat, acids and alkalis. Accordingly, there is no adaptability to mass production. Recently, we developed a convenient method for the low-cost, mass-production of antibodies using egg-laying hen ostriches. The ostrich egg is an excellent source of antibodies for industrial purposes. The present report shows that the ostrich antibodies have therapeutic effects in ailments such as atopic dermatitis, acne, pyoderma, and pollen allergies. We have successfully produced and purified ostrich immunoglobulin yolk (IgY) against pollen allergens (Cryj1, Cryj2, Chao1, Chao2) and found that allergic reactions were alleviated in skin patch tests of allergic patients by using the ostrich IgY. In addition, we produced ostrich IgY against the homogenates of Staphylococcus aureus and Propionibacterium acnes, and applied to dermal lesions of atopic dermatitis and acne patients, and then observed the therapeutic effects on the dermatitis of volunteer subjects.