Enzyme-linked immunosorbent assay (ELISA) has been used for measuring apolipoproteins A-I and B in the urine. ApoB is absent in urine of healthy subjects, and apoA-I is determined in trace quantity. In patients with chronic glomerulonephritis quantity of apoA-I in urine was 117 times as much as in control group. ApoB is present in urine of patients in considerable quantity (1528 +/- 315 micrograms/l). The ELISA method for determining apoA-I and apoB in urine makes it possible to evaluate the gravity of pathological process in kidney.