In recent years, the scientific publishing world has seen the creation and rapid growth of online journals, which do not respect the long-standing gentleman's agreement that has functioned as the primary quality-control mechanism for science: bona fide peer review and editorial oversight. Such predatory journals take advantage of the low cost and ease of online “publishing,” the open access movement, and use feigned associations with international standards and misleading claims of impact factors, aimed at deceiving researchers (especially inexperienced scientists) into believing they are legitimate. We present the history, evolution, and tactics of such journals, as well as recommendations for dealing with this threat to science itself.