Abstract: Objective To evaluate the long-term clinical outcomes of intravascular ultrasound（IVUS）in guiding the treatment of non-left main intermediate coronary lesions for patients of acute coronary syndrome (ACS). Methods A total of 25 patients with intermediate coronary lesions（stenosis of 40%-70%) confirmed by coronary angiography were performed with IVUS. When MLA≥4 mm2, we deferred the PCI treatment and performed optimal medical treatment (OMT). The patient were followed up for 12 month. The primary outcome was target vessel revascularization (TVR) and secondary outcome was major adverse cardiac events (MACEs). Results A total of 25 lesions of 25 patients were examined by IVUS. 19(76%) lesions were attenuated plaque, 4(16%)were echo-lucent plaque, 2(8%) were calcified plaque. Most of the plaque (18/25, 72%) were eccentric. Positive remodeling was found in 20(80%) lesions and negative remodeling in 5(20%) lesions with meanremodeling index of 1.17±0.15. Thrombus was found in 1 case, accounting for 4%. The diameter stenosis, area stenosis, minimal lumen area and the reference diameter mea-sured by IVUS were larger than those measured by quantitative coronary angiography (all P<0.05). One patient with non-ST segment elevated myocardiac infarction was performed revascularization because MI attacked again, and 2 patients with Unstable angina were treated with OMT but they were still rehospitalization because of angina occurred repeatedly. The incidence of TVR was 4.00%, so as 16.00% of MACE. Conclusion IVUS can be used to guide the treatment of non-left main intermediate coronary lesions for patients of acute coronary syndrome.