Introduction: Health tourism is one of the growing industries in the world. The main goal of this research was discovering the background model of word of mouth advertising in the development of health tourism.
Methods: In this research, the researcher has used a mixed approach. For this purpose, in the first study, in order to know the components of the background model of word of mouth advertising in the development of health tourism from the foundation data approach, and in the second study, the model was tested using a quantitative method. In the first study, the required data collection tool was the protocol and in-depth interview with eighteen hospital managers, and in the next step, the required data was distributed among 384 patients and the results were analyzed by AMOS  software.
Results: The researcher has conducted eighteen interviews to theoretical saturation and finally extracted 250 open codes and based on Strauss and Corbin's point of view, the analysis and results have been presented in the form of six main dimensions and thirty sub-dimensions.
Conclusion: The researcher presented his research in the form of a model including six dimensions, health tourism, brand equity of the health center brand, word of mouth advertising, quality of medical services, halal tourism, loyalty to the therapy center brand , and thirty sub-dimensions. Also, the results of the research have shown that the satisfaction with the treatment and medical staff and the accommodation of the patient and companion has a positive and significant effect on the increase of word of mouth advertising from the hospital and medical centers.