The Internet has become a chief health information source. It is posited that people who use the Web for health information must possess requisite eHealth literacy to avoid misuse. eHealth literacy refers to the skills in searching, retrieving, understanding, evaluating, and applying online health information to alter or maintain well-being. This research employed mixed methods of data collection, following a three-phase explanatory sequential design: (1) survey and eHealth literacy test, (2) focus group discussion, and (3) observational study, to describe the state of eHealth literacy of high school students in terms of their online health information seeking behaviors, search, retrieval, and evaluation strategies, actual eHealth literacy levels, and perceived eHealth literacy levels. Furthermore, the research aimed at investigating the relationships among school type, actual eHealth literacy levels, and perceived eHealth literacy levels. Results show that students are adept in searching and retrieving online health information. However, their evaluation strategies are suboptimal as they lack ability to check for content accuracy and source credibility. Findings also reveal a significant relationship between school type and perceived eHealth literacy levels, X[superscript 2] (2, N=263) =14.21, p=0.00, [alpha]=0.05. Private school students tend to score their perceived eHealth literacy levels higher. There is also a significant difference between actual eHealth literacy levels and perceived eHealth literacy levels, with students rating their perceived eHealth literacy levels (M=32.45, SD=6.10, N=40) higher than their actual eHealth literacy levels (M=29.13, SD=2.92, N=40), t(40)=4.16, p=0.000, [alpha]=0.05. It is concluded that while students are adept in computer and traditional literacies, they still need to further develop health and information literacies to effectively evaluate and apply the searched and retrieved online health information.