In the 21st century, in addition to “evidence-based medicine” (EBM), with its focus on life extension, “value-based medicine” (VBM), which considers quality of life (QOL) improvement, has become widespread. Assessment of QOL and patient-reported outcomes (PRO) in cost-effectiveness analysis―a mainstay of VBM―contributes to successful introduction of health technology assessment (HTA) in Japan. PRO is an umbrella term for a broad variety of concepts that measure the health status of patients as subjectively perceived by them. QOL and PRO differ in terms of concepts and depth they signify, but the latter often substitutes for the former as the subjectively reported endpoint of clinical trials, and is a term that covers perceived symptoms, physical functions, health satisfaction, and health-related QOL. This study explains the EuroQol-5 Dimensions (EQ-5D), a patient-reported outcome measure (PROM) whose application is exemplified in the official guideline issued by the Central Social Insurance Medical Council (Chuikyo) for the economic evaluation of drugs/medical devices. This study also discusses the importance and challenges of QOL/PRO measurements in cost-effectiveness analysis, as well as the need for international standardization for PROMs. Finally, it introduces the issues associated with the assessment of QOL/PRO in the trial introduction of cost-effectiveness analysis；that is, the necessity of evidence data, differences in evaluations of medicines and medical equipment, mappings that convert non-preference-based utility scores to preference-based EQ-5D scores in cases where preference-based utility scores were not measured during the clinical trials, and sensitivity analysis. HTA is thus expected to be adequately conducted in Japan.