The purpose of this research is to provide an available basis for marketing strategy by defining the cause-effect relation between the service level of staff members in dental clinic and purchasing behavior of the customers. This study was done in 10 days from November 2, 2009 to November 11, 2009 and the total 172 copies were used for the analysis. As a result of the correlation analysis, a significant positive correlation among all the measured variables was found. As a result of the structural model analysis, I found that the fair service among the variables of the service level significantly affects the building of relationship and the hospital image. The building of relationship and the hospital image significantly affect the positive oral spread. The building of relationship significantly affects the repurchase intentions but the hospital image does not affects the repurchase intentions. To sum up the result of this study, I found that the fair service and the building of relationship with patients are important variables in order to attract new patients and maintain existing customers. I recommend that the hospital continues to motivate staffs through internal marketing and conduct regular trainings. It is necessary to have patients satisfied with broadening responsibility and authority and set marketing strategy for the relationship with patients.