AbstractThe pre-launch accuracy prediction for the Hipparcos mission is reviewed with regard to the observed performance and expected lifetime of the satellite in its present orbit. Given the excellent quality of the data it is likely that the target accuracy of 2 milli-arcsec for typical programme stars can be achieved if operations continue at least until the end of 1993. We emphasize that any extension of the operational lifetime beyond that point strongly enhances the scientific value of the results.