Given the increasing importance of data quality for the ex situ conservation and utilization of plant genetic resources (PGR), an indicator was created that quantifies the level of completeness of passport data. This passport data completeness index (PDCI) uses the presence or absence of data points in the documentation of a genebank accession, taking into account the presence or value of other data points. For example, a wild accession should have a well-defined collection site but no variety name. Any type of accession, wild, landrace, breeding material or modern variety, can attain a maximal score of ten for this index. The applicability of this index was tested on the complete contents of EURISCO, the European catalogue of ex situ maintained PGR containing over one million records. Analysis of the PDCI of the material in EURISCO provided valuable insight in the data quality of European collections. The PDCI can be used to identify datasets that might need additional attention and improvement or datasets that need more careful interpretation than others.
