The ultimate goal of our research was to document for others the potential sources of accessible internal company data for public health and healthcare research, particularly in the area of pharmaceutical research, and, in doing so, to take the first steps toward exploring the current use and future potential for repositories of internal company information. Internal company documents serve as a valuable source of information about industry activities for those who wish to know about the impact of those activities upon the health of the public. Internal documents from pharmaceutical companies include not only information on marketing and policy activities but also contain quantitative and other data related to clinical trials carried out on company products. Data from all trials are critical for a complete and accurate assessment of interventions within systematic reviews. In response to this imperative, systematic reviewers and other healthcare stakeholders have been working hard towards making trial data held by companies publically available so that patients, providers, and policy makers can have a full picture of all that is known. Because internal company documents are not located in a single place, and they are not published or indexed in a bibliographic database, they are difficult to identify and locate. We elected to identify research articles using internal company documents across all industries as a starting point, knowing that we would likely leave many documents that are available for research unidentified. What we learned, first, is that thousands of internal tobacco company documents, mainly released through litigation, are located in repositories around the world, including searchable online repositories. Ninety percent of the research articles meeting our criteria used internal tobacco company documents and all but one of these used documents made available through litigation. The reference standard we used for articles employing internal tobacco documents indicated that our searches failed to find hundreds of additional, potentially eligible, studies of tobacco documents and that our searches also identified tobacco articles not included in the Tobacco Documents Library. The second thing we learned was that identification of nontobacco studies using internal company documents was harder than we had anticipated. Only 36/361 articles that we identified used non-tobacco sources, and more than half of these were concerned with pharmaceutical company documents. We made every effort to ensure a thorough search of PubMed and Embase databases to retrieve all relevant documents, and to be practical we designed a search strategy that elected precision over sensitivity. It is possible that there are additional relevant articles from other non-tobacco industries that our search failed to retrieve. We need to identify better search terms for retrieving articles that use internal company document.