Introduction Demographic changes since the second half of the last century have led to an aging population, and this is considered an important economic and social problem worldwide. In addition to the social, economic, and political effects of aging, the relationship between aging and health expenditure is also being recognized in recent years. The two main generally accepted underlying causes of aging populations are longer life expectancy and lower fertility. Thus, the aim of this study was to investigate the main causes of aging and the relationship between health expenditure and aging using causality econometric models on data samples from Turkey. Methods The Toda and Yamamoto causality approach, which is currently the preferred method, was chosen to obtain robust results on dual causality relationships between aging, fertility, life expectancy, and health expenditures. The data used in the estimation of causality were obtained from Organisation for Economic Co-operation and Development (OECD) statistics for Turkey, and the E-Views 8.0 econometric package program was used to predict causality. Results According to causality analysis, fertility rate resulted in population aging in Turkey for the period between 1975 and 2016, apart from a one-way causality between population aging and health expenditure in Turkey. Conclusion As aging has multiple social, political, and economic effects, the development and implementation of new policies toward the elderly and aging of population are very important.