The previous research on medical service loyalty has been focused on the cognitive path(service quality → brand trust → service loyalty). Despite the importance of affective perspective in medical service marketing, this topic has been given little attention in the service marketing literature. And there has been little academic study on the comprehensive model for medical service loyalty formation process. Furthermore, very little research has addressed main dimensions of brand personality in medical service environment. In order to address this void, this study suggests the comprehensive model for medical service loyalty formation process and investigates the significant role of affective path(brand personality → brand affect → service loyalty). The empirical results show that medical service loyalty is best described by the hypothesized model in which the cognitive and affective paths are included. Model comparison results demonstrate that brand affect has a significant positive effect on brand trust. This means that cognitive path and affective path is co-related. According to the empirical study, the components of brand personality in medical service environment are ``authority``, ``excitement``, ``competence``, ``devotion``, ``comfort`` and ``sincerity``. Based on these results, implications for effective medical service brand communication strategy are discussed.