Porcine colostrum and milk were separated into the acid-soluble fraction (SF) and casein frac-tion (CF) by centrifuge. Trypsin and chymotrypsin inhibitory capacity in porcine colostrum, milk and theircomponents were determined by incubating bovine trypsin or chymotrypsin in a medium. The inhibition of in-sulin-like growth factor Ⅰ (IGF-Ⅰ) and epidermal growth factor (EGF) degradation in pig small intestinal con-tents by porcine colostrum was measured by incubating iodinated IGF-Ⅰ or EGF. Degradation of labeled IGF-Ⅰor EGF was determined by monitoring the generation of radioactivity soluble in 30% trichloroacetic acid(TCA). The results showed that porcine colostrum had high levels of trypsin and chymotrypsin inhibitory ac-tivity and increased the stability of IGF-Ⅰ and EGF in pig intestinal contents. The SF was higher in inhibitorypotency than CF. The present study revealed that the protease inhibitors in porcine colostrum, milk-derivedand colostrum-specific, existed mainly in SF.