Soyabean lectin preparation (SBA) containing about 50% active lectin was given in a dose of 0.73 mg/g diet to 10 male rats for 31 days, while control group obtained the same diet without SBA. The performance and N balance were measured, then the rats were killed and activity of enzymes was measured in pancreas and plasma. The SBA supplementation had no significant effect on the diet intake, body weight gain, dry matter, and protein digestibility. However, it depressed N retention by an increase at N excretion in urine. The activity of amylase in plasma, the pancreas weight and trypsin activity in pancreas did not significantly differ between groups.