Soymilk was prepared by non-heated squeezing and then heated at various temperatures. For one-step heating, the precipitate produced by heating soymilk increased for heating at 70 and 80°C and was much less at 90°C or higher temperatures, showing that the dispersion stability of soymilk was dependent on the heating temperature. In the case of two-step heating (combinations of 115°C and a lower temperature), soymilk heated at 115°C in the first step and 70 or 80°C in the second step resulted in increased precipitation. Changes in protein surface hydrophobicity were considered to be related to the precipitate formation of soymilk heated at the two different temperatures, indicating the significance of heat denaturation and aggregate formation of proteins on the dispersion stability of soymilk.