  We have used archive HST WFPC2 data for three elliptical galaxies (NGC 3379
in the Leo I group, and NGC 4472 and NGC 4406 in the Virgo cluster) to
determine their distances using the Surface Brightness Fluctuation (SBF) method
as described by Tonry and Schneider (1988). A comparison of the HST results
with the SBF distance moduli of Ciardullo et al (1993) shows significant
disagreement and suggests that the r.m.s. error on these ground-based distance
moduli is actually as large as +-0.25 mag. The agreement is only slightly
improved when we compare our results with the HST and ground-based SBF
distances from Ajhar et al (1997) and Tonry et al (1997); the comparison
suggests that a lower limit on the error of the HST SBF distance moduli is
+-0.17 mag. Overall, these results suggest that previously quoted measurement
errors may underestimate the true error in SBF distance moduli by at least a
factor of 2-3.
