The fact that the patient satisfaction with primary care clinical practices and physician-patient communications has been decreased gradually has brought a new opportunity to online channel as a supplementary service to provide additional information. In this study, we adopted Expectation-Confirmation Theory (ECT) to examine the process of cognitive knowledge expectation-confirmation of e-healthcare users and recommended the attributes of “knowledge-intensive website”. An empirical study was conducted at the National Cancer Center (NCC), South Korea by evaluating its official website. The results indicated that all of our hypotheses were accepted: both pre-knowledge expectations and perceived performance (information quality, information presentation, and website attractiveness) positively influenced knowledge confirmation; knowledge confirmation had a positive and significant effect on perceived usefulness (post-expectations); and together with pre-expectations, both of these variables influenced user satisfaction. Discussion and implications for future research were also provided.