Background@#The effective evaluation of health information available online is an important skill. However, consumers' self-perceptions of their eHealth literacy levels do not reflect their actual capabilities. The goal of this experimental study of online search behavior is to identify differences between self-perceived eHealth literacy and actual ability to use the accuracy of cancer information available online. @*Methods@#Thirty-one adults participated in the study conducted on July 15 and 16, 2017. We first measured perceived eHealth literacy and then asked participants 5 questions concerning cancer. Bandicam (v3.3.0) and BrowsingHistoryView were used to record search behavior and uniform resource locators, respectively. A Mann-Whitney U test and Fisher's exact test were performed. @*Results@#The results showed that participants most frequently searched for cancer information on blogs and café websites. Regarding search behavior, those who perceived higher knowledge in available resources tended to solve the given problem with significantly smaller number of webpages to answer a weight management question. Participants who perceived higher knowledge in helpfulness of information tended to use significantly smaller number of webpages to answer questions on red ginseng's preventive effects on caner and weight management. However, there was no proof that the high eHealth literacy group had significantly higher rates of correct answers than the low eHealth literacy group. Further, regarding cancer screening, the rates of correct answers were low for groups who considered their ability higher to find helpful resources and perceived higher knowledge in helpfulness of information. @*Conclusion@#There is a gap between perceived eHealth literacy and the actual ability to use online cancer-related information. To fundamentally improve eHealth literacy, it is important to evaluate the actual abilities concerning each eHealth literacy component and to provide customized education.