Three clinical cases have been selected to focus on the role of thrombosis in unstable and refractory angina. The histories are abbreviated for simplicity. For example, it can be assumed that non-coronary causes of chest discomfort have been excluded, and that exacerbating factors such as anaemia, hyperthyroidism, hypoxia, arrhythmia, valve disease, obvious coagulopathy, and emotional stress have also been excluded by history, examination, and appropriate testing. These patients all underwent coronary angiography for severe symptoms associated with marked electrocardiographic or haemodynamic changes (and therefore did not undergo radionuclide stress testing) or for symptoms refractory to a medical regimen of rest, reassurance, oxygen, nitrates, cardioselective beta blockers, aspirin 325 mg once or twice daily, heparin 1000 U/h, and sometimes, calcium antagonists and sedatives.