Raw seeds (R) of pea (P), faba bean (F), and soybean (S) were extruded at 130, 150 or 170^oC, or boiled in water without previous soaking for 5, 10 or 20 minutes. Trypsin inhibitors activity (TIA) in raw seeds of P, F and S amounted 2.3, 2.1 and 31.3 and after extrusion at 170^oC it reached 0.1, 0.5 and 8.5 trypsin unit inhibited/mg sample (TIU/mg) in P, F and S, respectively. Ten minutes exposition in boiled water decreased TIA to 0.1, 0.1 and 0.4 TIU/mg, respectively. Haemagglutinin activity (HAA) assayed in raw seeds with guinea pig erythrocytes was 400, 100 and 800 in P, F and S, respectively. Extrusion at 170^oC decreased HAA to 100, 0 and 100 in P, F and S, respectively. Extracts from faba bean and pea which had been boiled for 20 minutes did not agglutinate human erythrocytes. However, boiled soybean still showed agglutination activity at 200, 200, 100 and 400 for blood groups: 0, A, B and AB, respectively. It is concluded that for nutritional purpose extrusion at 150oC is adequate for elimination of TIA and HAA in P and F, but in the case of S 170^oC is required. However, ten minutes of exposition of raw seeds to boiling water is effective for elimination of TIA. Boiling for twenty minutes canceled HAA in faba bean and pea protein extracts, but it was not so efficient in the case of soybean. Rats fed diets with 10% of extruded leguminous seeds (150^oC) had significantly increased apparent digestibility of dry matter and crude protein.