Even though the “user characteristics” (UC) can influence “acceptance” and “the continuance intention to use” of information systems such as electronic medical records (EMR), the effect of UC has not been adequately evaluated in post-adoption models. This study seeks to examine the effect of UC on post-usage of EMR using the expectation confirmation model (ECM). A total of 450 questionnaires was collected by a survey to extend ECM by integrating UC using structural equation modeling (SEM). Data were analyzed using LISREL through confirmatory factor analysis. A path analysis test was also performed to fit and confirm the model fit. The UC affects the “confirmation of expectations” directly and the “continuance intention to use” indirectly. The findings of the present study can provide a new path for further research on the extending of the ECM model. Moreover, end users’ characteristics should be considered in the preparation and training phases of EMR implementation.