Introduction: Intravascular ultrasound (IVUS) on long-term clinical outcomes in patients undergoing percutaneous coronary intervention (PCI) for chronic total occlusion (CTO) is not well established. This study aimed to evaluate IVUS-guided compared to angiography-only-guided CTO-PCI on acute angiographic result and 1-year clinical outcomes. Hypothesis: The application of IVUS in CTO-PCI could improve acute angiographic results and 1-year clinical outcomes for all-comers CTO patients. Methods: We analysed 528 consecutive patients undergoing CTO-PCI at a university affiliated hospital in Hong Kong from February 2009 to December 2016. Baseline characteristics, procedural characteristics, and 1-year clinical outcomes including cardiac death, non-fatal myocardial infarction (MI), target lesion revascularization (TLR), and composite target lesion failure (TLF) were evaluated. The use of IVUS, and the choice of PCI devices including plain old balloon angioplasty (POBA), bare metal stent (BMS), and drug eluting stent (DES), were at the discretion of the operator. Propensity score matching (PSM) was performed to reduce treatment selection bias and potential confounding factors. Results: 275 patients underwent 288 angiography-only-guided and 253 patients underwent 268 IVUS-guided CTO-PCI. IVUS-guided CTO-PCI was associated with higher procedural success compared to angiography-only-guided CTO-PCI (77.5% vs. 55.3%, p<0.01). DES were used more often in the IVUS-guided CTO-PCI group (85.3% vs. 65.6%, p<0.01) while BMS were used less in IVUS-guided CTO-PCI group (9.3% vs. 26.1%). After PSM for successful CTO stented patients, angiography-IVUS guidance was associated with more post stent balloon dilatation (84.7% vs. 56.3%, p<0.01), lower incidence of >20% residual stenosis (2.2% vs. 10.8%, p<0.01), longer total stent length (44.16±23.88mm vs. 33.52±18.90mm, p<0.01), and larger final angiographic stented diameter (3.12±0.63mm vs. 2.94±0.48mm, p<0.01). IVUS guided CTO-PCI was associated with lower 1-year TLF rates (3.0% vs. 10.0%, p=0.01). Conclusions: The use of IVUS was associated with higher success rates, more aggressive post-dilatation and better 1-year clinical outcomes compared to angiography-only guided CTO-PCI.