The purpose of this study is to determine the competitiveness level and competitiveness factors of the thermal health tourism sector of the South Aegean Thermal Tourism Development Region (İzmir, Manisa, Aydın and Denizli). First of all, the competitiveness levels of the thermal health tourism sector of the region were determined, and then the sub-variables of the competitive factors of the thermal health tourism sector were defined. Finally, suggestions were made to improve this level of competitiveness. The universe of the research; Medium and senior managers of thermal health tourism facilities operating in İzmir, Manisa, Aydın and Denizli provinces. In the study, in which quantitative research method was used, data was collected from 400 managers using face-to-face survey technique. The data were interpreted through SPSS and AMOS package programs, using frequency analysis, descriptive statistics, explanatory factor analysis (EFA) and confirmatory factor analysis (CFA) techniques. According to the results of the research, the level of competitiveness of the Thermal Health Tourism Sector of the South Aegean Thermal Tourism Development Region was determined at a medium level as a result of the analysis made with the diamond model. This result was achieved by taking into account the four main variables examined and the level of state contribution to the sector's competitiveness. Confirmatory factor analyses are performed; It has been determined that the thermal health tourism sector has an acceptable fit index for competitiveness factors. In the reliability analysis for the variables of the study, it was determined that the scales have high reliability levels.