The importance of good health of a population is crucial when determining social welfare. A new health-adjusted national income indicator that explores the relationships between economic growth, health and social welfare in Bangkok, Thailand from 1975 to 1999 is applied. This new approach to social welfare analysis is based on normative social choice theory, cost-benefit and systems analysis and is called (new)3 welfare economics. This paper argues that traditional measures of welfare, such as national income, fail to reflect accurately the impact of health on social welfare.