There are discussions on the use of real world data and real world evidence in relation to medicinal products. Real world data can be described as observational data that is not collected under experimental conditions (randomised clinical trials) but data generated in routine care from information related to a patient's treatment. It can come from patient registries, electronic health records, insurance data and web/social media. Real world evidence can be generated from such data sources according to a research plan. The research plan can be studies that are established to collect the data specifically for research purposes (primary data) or evidence coming from data collected for other purposes (secondary data). Examples of the use of real world evidence are: comparative effectiveness research and patient adherence studies; drug development (clinical feasibility studies, inform the design of pivotal trials); reimbursement (relative effectiveness assessment, marketing access arrangements).