Intravascular Ultrasound (IVUS) is a valuable adjunct to angiography, providing tomographic insights into coronary disease. Unlike angiography, which only depicts a 2D silhouette of the lumen, IVUS allows for the assessment of lumen area, plaque size, distribution, and composition. The safety of IVUS is well-documented, and it is particularly useful for evaluating luminal dimensions. Comparative studies show significant discrepancies between angiography and ultrasound after mechanical interventions, highlighting the need for IVUS in assessing complex lesions. IVUS can detect occult disease in angiographically normal sites and provide valuable information in ambiguous lesions, particularly for left main coronary disease. It has emerged as the optimal method for detecting transplant vasculopathy and identifying atheromas at risk of rupture. IVUS is also crucial in guiding interventional procedures, such as balloon angioplasty and atherectomy, by providing detailed images of plaque morphology and vessel wall characteristics. The technique has been instrumental in optimizing stent deployment and reducing restenosis rates. However, the precise clinical role of IVUS during intervention remains to be fully defined, and there is no consensus on optimal procedural endpoints. Future research aims to explore IVUS in regression-progression trials and novel therapeutic applications, such as percutaneous in-situ coronary artery bypass.Intravascular Ultrasound (IVUS) is a valuable adjunct to angiography, providing tomographic insights into coronary disease. Unlike angiography, which only depicts a 2D silhouette of the lumen, IVUS allows for the assessment of lumen area, plaque size, distribution, and composition. The safety of IVUS is well-documented, and it is particularly useful for evaluating luminal dimensions. Comparative studies show significant discrepancies between angiography and ultrasound after mechanical interventions, highlighting the need for IVUS in assessing complex lesions. IVUS can detect occult disease in angiographically normal sites and provide valuable information in ambiguous lesions, particularly for left main coronary disease. It has emerged as the optimal method for detecting transplant vasculopathy and identifying atheromas at risk of rupture. IVUS is also crucial in guiding interventional procedures, such as balloon angioplasty and atherectomy, by providing detailed images of plaque morphology and vessel wall characteristics. The technique has been instrumental in optimizing stent deployment and reducing restenosis rates. However, the precise clinical role of IVUS during intervention remains to be fully defined, and there is no consensus on optimal procedural endpoints. Future research aims to explore IVUS in regression-progression trials and novel therapeutic applications, such as percutaneous in-situ coronary artery bypass.