Other ; There is agreement in the biomedical research community that data sharing is key to making science more transparent, reproducible, and reusable. Publishers could play an important role in facilitating data sharing; however, many journals have not yet implemented data sharing policies and the requirements vary across journals. To assess the pervasiveness and quality of data sharing policies, we curated the author instructions of 318 biomedical journals. The policies were reviewed and coded according to a rubric. We determined if if data sharing was required, recommended, or not addressed at all. The data sharing method and licensing recommendations were examined, as well any mention of reproducibility. The data was analyzed for patterns relating to publishing volume, Journal Impact Factor, and publishing models (Open Access or subscription). 11.9% of the journals stated that data sharing was required as a condition of publication; 9.1% of the journals required data sharing, but did not make clear it would affect publication decisions; 23.3% of the journals only encouraged authors to share data; 9.1% of journals mentioned data sharing indirectly; and 14.8% only addressed protein, proteomic and/or genomic data sharing. There was no mention of data sharing in 31.8% of the journals. Impact factors were significantly higher for journals with the strongest data sharing policies compared to all other data sharing mark categories. Open access journals were not more likely to require data sharing. Our study showed only a minority of biomedical journals require data sharing, and a significant association between higher Impact Factors and journals with a data sharing requirement. We found that most data sharing policies did not provide specific guidance on the practices that ensure data is maximally available and reusable. As a continuation of this work, we plan to build a curated public database of journal data sharing policies, and convene a community of stakeholders to further work on recommendations for strengthening and communicating journal data sharing policies.