These proceedings contain the papers presented at the Bayer-Symposium V which was held in Grosse Ledder on October 16-21, 1973 and which was simultaneously the Second International Research Conference on Proteinase Inhibitors. The cordial atmosphere, the frank discussions and the profitable exchange of ideas during the First International Research Conference on Proteinase Inhibitors which was held on November 4--6, 1970 in Munich were a stimulant for us to consider holding a Second Conference especially as the steadily increasing research activities in this and related fields called for a new...