Medical products is equiped with wide variety and high-tech features. The high involvement of professional produces promoted customer loyalty is importance issue in the medical market. This purpose of this research is to explore the relationship between medical product involvement and customer loyalty. To test whether product category has moderating effects on the relationship between involvement and customer loyalty. Survey method was conducted by gathering the questionnaires from the Medical center, the Regional and the District hospital in Taiwan. 420 questionnaires were sent out to the hospital. In total, 394 questionnaires were collected to be effective. Data analysis was applied the t-test, one-way ANOVA, Pearson correlation analysis, and the hierarchical regression method. The findings showed that there is significantly positively relationship between medical product involvement and customer loyalty. Product category has moderating effects on the relationship between involvement and customer loyalty. Based on the research findings, suggestions reference are made for further studies and practice.