This systematic review investigates whether pharmaceutical industry sponsorship of drug studies influences research outcomes and the quality of trials. The study analyzed 30 studies and found that research funded by pharmaceutical companies was less likely to be published than research funded by other sources. Studies sponsored by pharmaceutical companies were more likely to show outcomes favorable to the sponsor, with an odds ratio of 4.05 (95% confidence interval 2.98 to 5.51). None of the 13 studies that analyzed methods reported that industry-funded studies were of poorer quality. The review highlights systematic bias favoring products made by the company funding the research. Possible explanations include the selection of an inappropriate comparator and publication bias. The study also found that research funded by the pharmaceutical industry was more likely to be published in symposium proceedings than non-industry sponsored research. Additionally, pharmacoeconomic studies sponsored by the drug industry were more likely to report results favoring the sponsor's product. The study concludes that there is some kind of systematic bias in the outcomes of published research funded by the pharmaceutical industry. The results suggest that publication bias may explain the favorable outcomes of industry-funded research. The study also notes that the methods of industry-funded trials were at least as good as those of non-industry funded research, but the absence of peer review may result in an overly favorable interpretation of the results. The study has limitations, including the difficulty in locating research examining the effects of company sponsorship and the inability to critically evaluate the methodology in the abstracts and journal letters. The study emphasizes the need for more rigorous criteria for the acceptance of research sponsored by industry and the importance of prospective registration of all clinical trials to prevent publication bias.This systematic review investigates whether pharmaceutical industry sponsorship of drug studies influences research outcomes and the quality of trials. The study analyzed 30 studies and found that research funded by pharmaceutical companies was less likely to be published than research funded by other sources. Studies sponsored by pharmaceutical companies were more likely to show outcomes favorable to the sponsor, with an odds ratio of 4.05 (95% confidence interval 2.98 to 5.51). None of the 13 studies that analyzed methods reported that industry-funded studies were of poorer quality. The review highlights systematic bias favoring products made by the company funding the research. Possible explanations include the selection of an inappropriate comparator and publication bias. The study also found that research funded by the pharmaceutical industry was more likely to be published in symposium proceedings than non-industry sponsored research. Additionally, pharmacoeconomic studies sponsored by the drug industry were more likely to report results favoring the sponsor's product. The study concludes that there is some kind of systematic bias in the outcomes of published research funded by the pharmaceutical industry. The results suggest that publication bias may explain the favorable outcomes of industry-funded research. The study also notes that the methods of industry-funded trials were at least as good as those of non-industry funded research, but the absence of peer review may result in an overly favorable interpretation of the results. The study has limitations, including the difficulty in locating research examining the effects of company sponsorship and the inability to critically evaluate the methodology in the abstracts and journal letters. The study emphasizes the need for more rigorous criteria for the acceptance of research sponsored by industry and the importance of prospective registration of all clinical trials to prevent publication bias.