Abstract: The present invention is concerned with new compounds, and particularly those having a fused bicyclic ring substituted with an amidine moiety. These compounds are each potent inhibitors of Factor D of the alternate pathway of complement, C1s of the classical pathway of complement, Factors Xa, XIIa, VIIa and thrombin of the coagulation pathway, plasmin in the fibrinolytic pathway, and kallikrein and high molecular weight kininogen in the inflammatory pathways. These proteases, which have serine in their active site, are called serine proteases and they are pivotal to most of the processes of inflammation and coagulation. In fact, these various systems are interactive with one another and it is difficult to activate one pathway without it influencing the others.