Testosterone-estradiol binding globulin (TeBG) is known to change in various endocrinological environments such as estrogen administration, pregnancy and aging. Several methods, including dextran coated charcoal, equilibrium dialysis and ammonium sulfate precipitation, were used to measure the binding capacity of TeBG, but these were not simple and accurate. We therefore measured TeBG levels in human serum by means of a steady state polyacrylamide gel electrophoresis and found that this method was simple and accurate for the determination of the binding capacity of TeBG. The value of TeBG in normal adults (27 approximately 32 years old) was 3.88 +/- 0.45 x 10(-8) Mol and in patients with benign prostatic hypertrophy the value was high (5.49 +/- 1.35 x 10(-8) Mol compared to that of normal adults.