The debate over access to medicines has principally centered on pharmaceutical patents and prohibitively high drug prices. Although a less recognized problem, counterfeit pharmaceuticals are certainly a more insidious barrier to access. Pharmaceutical counterfeiting is an invisible threat, not only by nature, but also because the industry has historically downplayed it. However, that has changed. Pharmaceutical firms now not only readily concede counterfeiting is a threat to their business, but in some cases publicly address their strategies and the anticounterfeiting technologies in use and development. Acknowledging the problem has benefited the industry because it alters the ways in which firms are able to combat counterfeiting, allowing them to more overtly confront the problem. In addition, it allows them to better partner with governments and health advocates since their incentives are aligned in efforts to prevent counterfeiting. In light of the more public and more aggressive campaign against counterfeiting, it is important to examine the variety of strategies firms may utilize to prevent their sale. Through a theoretical model of the market in a representative developing country, several anticounterfeiting strategies are considered. Some strategies appear to be more effective than others in the battle against fake drugs. Copyright © 2007 John Wiley & Sons, Ltd.