The need for economic evaluation of new health care technologies, especially in the modern world era, is undisputable. Economic evidence alongside clinical evidence are the two main pillars of the Health Technology Assessment (HTA), a process which is followed for reimbursement medical technologies and budget allocation decisions. The role of epidemiological research is essential in obtaining the necessary data for the development of the economic evaluations. In this review paper, we adopt a stepwise approach, based on current guidelines for conducting economic evaluation (both budget impact and cost effectiveness analyses) for highlighting the need for modern epidemiological methods and tools in such a process. Epidemiological studies provide the data for the eligible patient population, the prevalence and incidence of disease, treatment effectiveness and health care resource utilization; these, in turn, are synthesized in an appropriate framework, together with real world data, for assisting in the budget allocation decisions.