BACKGROUND: Are we witnessing the beginning of the development of a new sub-discipline of health economics? The purpose of the paper is to outline the main theoretical arguments for the establishment of a new research tradition on ‘public health economics’ combining public economics with health economics. METHODS: The results from a systematic literature search in PubMed and NHSEED on the term ‘public health economics’ were presented and discussed at a workshop at the Danish public health conference in Nyborg September 22, 2009. Among the invited participants were health economists, public health researchers, HTA-advisors, econometricians, and decision makers. RESULTS: Three main theoretical arguments were identified: 1) There is a need for developing new methods for the economic evaluation of public health interventions. 2) Economic evaluation of health care may be seriously misleading if public health research is ignored. 3) The entire health economic research tradition may benefit from encompassing a more socioeconomic model of health. CONCLUSIONS:   There is limited tradition yet for health economists and researches within public health to work together and meet regularly, no scientific journal specifically oriented towards public health economics, and no textbook in health economics that include research from all these related areas.  Thus, the research environment is to some extent characterised by lack of cooperation, which may constitute an obstacle for the development of a consistent and coherent line of economic research in the field of public health.