Unstable angina occurs in a heterogeneous population of patients. In the subset of patients with recent rest angina, both angiographic and angioscopic studies have suggested that coronary artery thrombus is often present and serves as a predictor of subsequent adverse clinical events, including recurrent angina, myocardial infarction, the need for urgent coronary revascularization, and death. Studies of thrombolytic therapy in small populations of patients with unstable angina suggest it may lyse coronary thrombus, raise the ischemic threshold, and possibly have a favorable influence on clinical outcome. Large multicenter trials of patients with unstable angina and non-Q-wave infarction have been designed to answer several questions: Will rt-PA produce improvement in angiographically determined coronary arterial stenoses? Is rt-PA superior to conventional therapy? Is there a need for routine angiography, followed by revascularization, in suitable patients? Until these questions are answered, the role of thrombolytic therapy in patients with unstable angina remains speculative.