Two types of proteinase inhibitors were purified from Enterolobium contortisiliquum beans. The inhibitor of serine-proteinases inhibited trypsin (Ki = 5 nM), chymotrypsin (Ki = 10 nM) and plasma kallikrein, but not tissue kallikreins. The molecular weight is approximately 23 kDal and two polypeptide chains are detected after reduction. The second inhibitor with activity directed against SH-proteinases was isolated by CM-papain-Sepharose. The molecular weight is approximately 60 kDal and only one polypeptide chain was detected after reduction. Papain (Ki = 0.6 nM) and bromelain are inhibited.