Amidino and benzamidino compounds, including compounds of the formula: ##STR1## wherein R.sup.1 -R.sup.4, R.sup.6 -R.sup.9, Y, Z, n and m are set forth in the specification, as well as hydrates, solvates or pharmaceutically acceptable salts thereof, that inhibit proteolytic enzymes such as thrombin are described. Also described are methods for preparing the compounds of Formula I.