Journal of Medical Internet Research - International Scientific Journal for Medical Research, Information and Communication on the Internet #Preprint #PeerReviewMe: Warning: This is a unreviewed preprint. Readers are warned that the document has not been peer-reviewed by expert/patient reviewers or an academic editor, may contain misleading claims, and is likely to undergo changes before final publication, if accepted, or may have been rejected/withdrawn. Readers with interest and expertise are encouraged to sign up as peer-reviewer, if the paper is within an open peer-review period. Please cite this preprint only for review purposes or for grant applications and CVs (if you are the author). Background: Previous studies suggest that patient's online health information seeking affects medical consultations and patient-doctor relationships. An up-to-date picture of patients’ online health information seeking behaviors can inform and prepare frontline healthcare professionals to collaborate, facilitate or empower patients to access and manage health information online. Objective: This study explores the prevalence, patterns, and predictors of online health information seeking behaviors among primary care patients in Hong Kong, and the relations between online health information seeking and eHealth literacy. Methods: Patients attending a university primary care clinic in Hong Kong were asked to complete a questionnaire survey on their demographic backgrounds; health status; frequency and pattern of online health information seeking; contents, sources, and reasons of online health information seeking, and their eHealth literacy. eHealth literacy was measured by the validated eHealth Literacy Scale (eHEALS). Regression analyses explored various demographic and behavioral predictors to online health information seeking, and predictors to eHealth literacy. Results: 97.3% (1162/1194) respondents used the Internet, of which 87.4% (1016/1162) had used the Internet to find health information. Most respondents (66.0%, 665/1008) searched once monthly or more. Few (26.7%, 271/1016) asked their doctor about health information found online, but most doctors (56.1%, 152/271) showed little or no interest at all. The most sought topic was symptom (81.6%, 829/1016), the top reason was noticing new symptoms or change in health (70.1%, 712/1016), the most popular source is online encyclopedia (70.0%, 711/1016), and the top reason for choosing a source was convenience (55.4%, 563/1016). Poisson regression analysis identified high eHEALS score, fair or poor self-rated health, having chronic medical condition, and using the Internet several times a day as significant predictors to online health information seeking. Multiple regression analysis identified lower age, better self-rated health, more frequent Internet use, more frequent online health information seeking, and more types of health information sought as significant predictors to higher eHealth literacy. Conclusions: OHIS is prevalent among primary care patients in Hong Kong, but only a minority shared the information with doctors. Websites were chosen more for convenience than for accuracy or authoritativeness. Doctors should recognize, facilitate and empower patients for OHIS.