Preview The risk-benefit ratio of oral anticoagulant therapy is of special concern in the 1990s, because potential uses of these agents are expanding rapidly. A careful review of all aspects of therapy with patients new to anticoagulants may improve compliance and lessen the incidence of bleeding, the major complication. Dr Brigden provides case reports to illustrate risk factors for bleeding, approaches to determining the source, and management of elevated prothrombin time.