Serum immunoglobulin concentrations in allergic and other diseases were measured by radioimmunosorbent technique (R.I.S.T.) and single radial immunodiffusion. In allergic diseases, especially atopic dermatitis and reaginic group of asthma, IgE and D were markedly elevated, while IgG, A and M were within normal range and there appeared almost no difference in them among allergic diseases, reaginic and non-reaginic groups. In cirrhosis, among liver diseases, all immunoglobulin levels, especially IgE level, were significantly raised, i.e.IgE 10, IgD 2.6, IgA 2.1, IgM 1.9, and IgG 1.5 times as high as those of control group respectively. Serum immunoglobulins were studied also in cancer, uremia, SLE and diabetes mellitus. In any diseases presently examined, lower levels of immunoglobulins (IgG, A, M, D, E) than normal were not detected.