The aim of this work is to give an overview of recent developments of journal data sharing policies, with summary and examples of standardised guidelines for journal publishers. In addition, it examines the prevalence of journal data policies in Croatian journals and explores the content of these policies. To give an overview of the current state of data sharing policies, published articles that review existing journal data policies and develop model data policies or guidelines for journals were identified and examined. For the analysis of Croatian journals, data was collected from the Hrčak portal, using a software script for harvesting journal metadata and attached files from the portal. Searching for content related to data archiving through downloaded files was done using the following keywords: 'data', 'deposit', 'archiving', 'supplement', including Croatian variants and different grammar forms. The search process was facilitated by using software tools that extracted lines of text from source documents containing defined keywords, together with two lines of text above and below the position of keywords in the text as context. The script parses through documents and creates one file containing file name of the identified document and snippets of extracted text from that document. Created file is than manually examined to identify journals that have any content related to research data and eliminate content that is related to data in another context. A dataset is created which contains journal metadata and coded information about the content of the policy. Coding framework for the analysis of content related to research data in journal editorial documents was developed based on previous research (1, 2) and adapted for this analysis. Results and Discussion Recent studies (1, 2, 3) show lack of clear data sharing and transparency policies in the majority of journals. Where the policies were present, wide variety in quality of existing policies was found. This is an obstacle in the practice of data sharing, especially for the authors who need clear guidelines on how to deposit and make their data transparent and available for others to re-use. Standardisation of data policies could help journal editors and research funders to formulate clear mandates and recommendations that can influence the development of research transparency culture. Several attempts to develop a model data policies are identified in recent years, and the most prominent existing implementation guidelines for journals, publishers and funders are: Research data for journal editors by the Australian National Data Service(4), Transparency and Openness Promotion (TOP) Guidelines by the Center for Open Science(5), Research Data Policy Framework for all journals and publishers by Data policy standardisation and implementation Interest Group (IG) of the Research Data Alliance (RDA)(6), Journal Research Data Policy Model Framework by The Journal Research Data (JoRD) Project, funded by JISC (Joint Information Systems Committee)(2). These guidelines identify the key elements of a good data policy such as data citation, data repositories, data availability statements, data standards and formats, and peer review of research data. Although all of them attempt to establish standard features, they provide flexibility for adoption depending on disciplinary variation. In order to find out if Croatian journals are implementing and promoting data sharing policies, the analysis of data policies of Croatian journals was conducted. Preliminary results, based on a sample of editorial documents, show that around 15% of journals mention research data in their policy and guidance documents, whether the statement expresses only the general principle of research transparency or the statement is a requirement. Journals that explicitly mention data access and retention are usually referring to the outdated ALPSP-STM Statement on data and databases. Conclusion Data sharing is encouraged in contemporary research environment. Journals in the stage of planning to implement research data policy might find it very useful to consult existing guidelines and follow examples of good practice presented in this work. Some Croatian journals started to adopt basic data sharing policies and transparency principles, but often it is not clear how and if the existing policies are enforced.