The article discusses the use of the Quality-Adjusted Life Year (QALY) as a primary measure in economic evaluations of healthcare interventions. QALYs combine both the quantity and quality of life, providing a standardized way to compare different treatments across various disease areas and populations. Key studies and methods for valuing health states, such as utility measurement, are highlighted. The article addresses areas of agreement and controversy, including the limitations of the QALY approach in capturing health benefits, its blindness to equity concerns, and the theoretical assumptions underlying it. It also explores the debate on whether QALYs should be valued equally regardless of who accrues them and the issue of who should value health states. The article concludes by discussing challenges and potential alternatives to the QALY approach, such as the Disability-Adjusted Life Year (DALY), Healthy Years Equivalent (HYE), and Willingness-to-Pay (WTP) methods. Despite these challenges, the QALY remains a cornerstone in economic analysis, but improvements are needed to address equity and other methodological issues.The article discusses the use of the Quality-Adjusted Life Year (QALY) as a primary measure in economic evaluations of healthcare interventions. QALYs combine both the quantity and quality of life, providing a standardized way to compare different treatments across various disease areas and populations. Key studies and methods for valuing health states, such as utility measurement, are highlighted. The article addresses areas of agreement and controversy, including the limitations of the QALY approach in capturing health benefits, its blindness to equity concerns, and the theoretical assumptions underlying it. It also explores the debate on whether QALYs should be valued equally regardless of who accrues them and the issue of who should value health states. The article concludes by discussing challenges and potential alternatives to the QALY approach, such as the Disability-Adjusted Life Year (DALY), Healthy Years Equivalent (HYE), and Willingness-to-Pay (WTP) methods. Despite these challenges, the QALY remains a cornerstone in economic analysis, but improvements are needed to address equity and other methodological issues.