Calves fed a milk replacer containing alkali-treated fully cooked soy flour as the only source of protein grew as well as calves receiving acid-treated flour and more rapidly than calves fed untreated flour. Growth in weanling rats fed either acid-treated or alkali-treated soy flour was superior to that for rats fed untreated flour. No evidence was obtained to suggest the presence of a pH-labile water-soluble growth inhibitor in the untreated flour. © 1969, American Dairy Science Association. All rights reserved.