  We use a sample of 20 poor groups of galaxies to study the low L_x tail of
the L_x-sigma relationship. We have obtained redshifts for fainter members and
deep X-ray imaging of these groups. We find that the L_x-sigma relationship
derived for the rich clusters in the sample of Mushotzky & Scharf (1997) is
consistent with the data for our 20 poor groups. However, it is not possible to
reach strong conclusions about differences in the L_x-sigma relationship for
groups and clusters in general at the present time because of significant
differences between various cluster samples.
