  We use the Updated Zwicky Catalog of galaxies (Falco et al. 1999) to generate
a catalog of groups, by means of a friend-of-friend algorithm. The correlation
length of the total sample is well fitted with a power law $
\xi(r)=(r/r_0)^\gamma $ with parameters $r_0=9.0 \pm 0.4 h^{-1}Mpc$ and $\gamma
= -1.67 \pm 0.09$ for values of $r<70 h^{-1} Mpc$. Three subsamples defined by
the range of group virial masses ${\cal M}$ were used to have their clustering
properties examined throughout the autocorrelation function. We find an
increase of the amplitude of the correlation function according to the group
masses which extends the results of the $ r_0-d_c$ relation for galaxy systems
at small $d_c$. For completeness we have also analyzed a sample of groups
obtained from the Southern Sky Redshift Survey (da Costa et al.1998) in the
range of virial masses $5\times10^{12}M_{\odot}<{\cal
M}<4\times10^{14}M_{\odot} $ to compare the results with those obtained from
GUZC.
