Two adsorption techniques were studied as potential methods for the recovery of aprotinin: a biospecific adsorption (using immobilized trypsin and chymotrypsin as ligants) and a pseudobiospecific adsorption of aprotinin-trypsin complex onto IMAC matrix. These studies indicated that ionic strength has an important effect on aprotinin adsorption on immobilized trypsin, and the pH was the most significant variable in aprotinin desorption from both immobilized enzymes. The aprotinin-trypsin complex adsorption onto the IMAC matrix was not as significantly affected by changes in pH as it was for changes in ionic strength. For the desorption step, both variables significantly affected the complex recovery. However, the effect of ionic strength was markedly stronger for this desorption step.119127Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)