This case report describes a 58-year-old female suffering from unstable angina pectoris showing two-stem disease with occlusion of the left anterior descending artery at angiography. Due to continuous symptoms and ECG-deviations, percutaneous transluminal coronary angioplasty of the occlusion was performed twice with primary success. However, acute re-occlusion with angina and ECG-changes developed after 6 and 2 h, respectively. For technical reasons, immediate bypass surgery was impossible and thus, patient underwent a third dilatation followed by infusion of ketanserin (0.1 mg/min), a S2-serotonergic receptor antagonist, for 24 h. During this period, patient was without complaints and showed normal ECG. Hematocrit fell and viscosity as well as elasticity improved markedly by ketanserin. Renewed angina and ECG-deviations developed 2 h after discontinuation of ketanserin therapy and patient had to undergo coronary artery bypass grafting.