Genetic modification is the process by which genes of dissimilar and unrelated species are combined in a laboratory, permanently altering the genetic codes of the new organism. This technology is radically different from traditional breeding techniques and raises profound health, environmental, economic, and ethical questions. U.S. regulatory agencies determined genetically modified foods to be "substantially equivalent" to conventional crops, and therefore do not require that genetically engineered crops to undergo any safety testing before they go to market. This paper looks at available published research on the health risks and safety of genetically engineered foods to assess the amount of research that has been done to evaluate these risks; examine the health risks posed by genetically engineered crops; and determine what gaps exist in the research. In a search of Medline, the National Library of Medicine's online database, and Toxline, the online database of toxicology bibliography, I encountered 15 studies on health effects and safety of genetically engineered foods and 4 of these studies were done by biotechnology industry that has an economic interest in finding favorable results. These studies found indications that genetically engineered foods may cause allergic reactions; have unpredictable effects such as increased toxicity; and may lead to increased antibiotic resistance. There are also many gaps in the existing research, mainly because so little research was found to assess the health risks of genetically engineered foods. There have not been studies to determine the allergenicity of all novel proteins and all Bt crops, which have a likelihood of becoming allergens. Many genetically engineered foods have never undergone a toxicological assessment to determine what toxic impacts they may have when consumed. Additionally, studies have indicated that genes from genetically engineered foods can survive passage through the human gut, and more research is needed to determine the implications for antibiotic resistance, among other risks. The amount of research and findings of health risk in many of these studies make it curious, at best, that the FDA has determined genetically engineered foods to be substantially equivalent to non-genetically engineered foods, and makes it clear that this does not certify the safety of these foods. There is a serious need for more research to be done to further determine the health risks posed by genetically engineered foods. Until these studies are done and the health risks of genetically engineered foods are more fully understood, the public should not consume these foods.