Seed flour from Moringa oleifera is widely used as a natural coagulant for water treatment in developing countries. Extracts obtained by water soaking of M. oleifera intact seeds were investigated for the presence of lectin, trypsin inhibitor, tannin as well as antioxidant activity. A water soluble M. oleifera lectin (WSMoL) detected was mainly active with rabbit cells at pH 4.5; heat treatment, pH 7.0, fructose and porcine thyroglobulin abolished HA of WSMoL. Trypsin inhibitor or tannins were not detected; the antioxidant component (WSMoAC) reduced 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) was slower than catechin and was thermostable. The extracts showed a primary glycopolypeptide band of Mw 20,000; the main native acidic protein showed hemagglutinating activity. WSMoL may be involved in seed coagulant properties.