A number of studies have reported empirical estimates of ozone loss in the Arctic vortex.They have used satellite and in situ measurements and have principally covered the Arcticwinters in the 1990s. While there is qualitative consistency between the patterns of ozone loss, aquantitative comparison of the published values shows apparent disagreements. In this paper weexamine these disagreements in more detail. We choose to concentrate on the five maintechniques (Match, Système d'Analyse par Observation Zénithale (SAOZ)/REPROBUS,Microwave Limb Sounder (MLS), vortex average descent, and the Halogen OccultationExperiment (HALOE) ozone tracer approach). Estimates of the ozone losses in three winters(1994/1995, 1995/1996 and 1996/1997) are recalculated so that the same time periods, altituderanges, and definitions of the Arctic vortex are used. This recalculation reveals a remarkably goodagreement between the various estimates. For example, a superficial comparison of results fromMatch and from MLS indicates a big discrepancy (2.0 ± 0.3 and 0.85 ppmv, respectively, for airending at ~460 K in March 1995). However, the more precise comparisons presented here revealgood agreement for the individual MLS periods (0.5 ± 0.1 versus 0.5 ppmv; 0.4 ± 0.2 versus0.3-0.4 ppmv; and 0.16 ± 0.09 ppmv versus no significant loss). Initial comparisons of the columnlosses derived for 1999/2000 also show good agreement with four techniques, giving 105 DU(SAOZ/REPROBUS), 80 DU (380-700 K partial column from Polar Ozone and Aerosol Monitoring(POAM)/REPROBUS), 85 ± 10 DU (HALOE ozone tracer), and 88 ± 13 (400-580 partial columnfrom Match). There are some remaining discrepancies with ozone losses calculated using HALOEozone tracer relations; it is important to ensure that the initial relation is truly representative of thevortex prior to the period of ozone loss.