Importing data, to make them available for other services (R/DataSHIELD analysis, reporting, making a data web portal etc.), is a fundamental feature of a data warehouse. Opal supports many different import formats from various sources (files, remote servers). There are also many different ways of triggering an import task (manually or using a script). Opal also offers to have a rich description of the data: data dictionary can contain useful information about the data origin and constitutes the first step to build a web data portal useful for researchers.