Corporate diversification allows for well-hidden financial ties between pharmaceutical and tobacco companies, which can cause a conflict of interest in the development and marketing of pharmaceutical products. In our investigation of tobacco company documents released and posted on the Internet as a result of the Master Settlement Agreement, we have found that these financial ties have fostered both competition and collaboration between the tobacco and pharmaceutical industries. We present 3 case studies. One shows how tobacco companies pressured pharmaceutical companies to scale back their smoking cessation educational materials that accompanied Nicorette. The second shows how they restricted to whom the pharmaceutical company could market its transdermal nicotine patch. In the third case, we show how subsidiary tobacco and pharmaceutical companies of a parent company collaborated in the production of a nicotine-release gum. Thus, because tobacco cessation product marketing has been altered as a result of these financial conflicts, disclosure would serve the interest of public health.