The clinical value of the immunological tests performed routinely has been evaluated in 91 patients with various histological types of glomerulonephritis. An antigen possibly involved in the pathogeny of renal disease was found in 24% cases. However, in most instances no direct link between the presence of this given antigen and the disease could be observed. Therefore systematic investigations for antigens should be restricted to dosages of antistreptolysin and antinuclear antibodies and to determination of Hbs antigen. Immune complexes, which were observed in many cases, were of no discriminant value for the clinician. Dosages of the complement fractions and the determination of cryoglobulins can be helpful for diagnostic, follow-up and treatment. Our results justify a restricted selection of the routine immunological tests used in patients with glomerulonephritis. More specific investigations remain useful when they are clinically oriented.