The article discusses the assessment of endothelial function in humans and its clinical relevance. Endothelial dysfunction is a key pathological condition associated with most cardiovascular risk factors. While endothelial function can be measured in research, its use as a clinical tool is not yet established. The review outlines common methods to assess vascular function, their advantages and disadvantages, and clinical settings where endothelial function measurements may be valuable. It emphasizes that endothelial function is not only a risk marker but may also provide prognostic information beyond traditional risk scores, particularly in primary prevention and in patients with established coronary disease. Non-invasive endothelial function measurements offer valuable additional information, but further research is needed to determine if they can guide treatment and improve outcomes. The review also discusses the clinical implications of endothelial dysfunction in populations and individuals, highlighting its association with cardiovascular risk factors and its role in predicting future events. Endothelial function measurements, such as flow-mediated vasodilation (FMD) and peripheral arterial tonometry (PAT), have shown prognostic value in certain patient populations. However, their use in clinical practice is not yet recommended by guidelines due to the lack of clear additional prognostic value and standardized methodologies. The article also explores the role of endothelial function in drug development and the need for future studies to assess its potential in guiding therapy and improving outcomes. Overall, endothelial function measurements may provide important insights into vascular health and disease progression, but further research is needed to fully understand their clinical utility.The article discusses the assessment of endothelial function in humans and its clinical relevance. Endothelial dysfunction is a key pathological condition associated with most cardiovascular risk factors. While endothelial function can be measured in research, its use as a clinical tool is not yet established. The review outlines common methods to assess vascular function, their advantages and disadvantages, and clinical settings where endothelial function measurements may be valuable. It emphasizes that endothelial function is not only a risk marker but may also provide prognostic information beyond traditional risk scores, particularly in primary prevention and in patients with established coronary disease. Non-invasive endothelial function measurements offer valuable additional information, but further research is needed to determine if they can guide treatment and improve outcomes. The review also discusses the clinical implications of endothelial dysfunction in populations and individuals, highlighting its association with cardiovascular risk factors and its role in predicting future events. Endothelial function measurements, such as flow-mediated vasodilation (FMD) and peripheral arterial tonometry (PAT), have shown prognostic value in certain patient populations. However, their use in clinical practice is not yet recommended by guidelines due to the lack of clear additional prognostic value and standardized methodologies. The article also explores the role of endothelial function in drug development and the need for future studies to assess its potential in guiding therapy and improving outcomes. Overall, endothelial function measurements may provide important insights into vascular health and disease progression, but further research is needed to fully understand their clinical utility.