The Internet has become a favored source to find health information. Worldwide, about 4.5% of all Internet searches are for health-related information. However, research has found that the quality of online health information is mixed, which raises serious concerns about the impact of this information. This paper reviews relevant research to understand how health information on the Internet is retrieved, evaluated, and used. Most users of online health information are looking for information about specific health conditions because they or someone they know was diagnosed with a medical condition. They typically use general search engines to find online health information and enter short phrases, often misspelled. They seldom go beyond the first page of a search. Both their search and evaluation skills are limited although they are concerned about the quality of online health information. They avoid sites with overt commercialism, but often do not pay attention to indicators of credibility. Online health information is used to fill an information void which can enhance coping and self efficacy, affects health-related decisions and behavior of users and their friends and family, and is often discussed with health care providers. There are cross-cultural differences in the types of sites used as well as how online information is used. Based on the research reviewed in this paper, three major recommendations are suggested. Professionals should recommend sites. Professionals should promote more effective search and evaluation techniques. Professionals should be involved in developing and promoting uniform standards for health and mental health sites.