  A sample of almost 400 Gamma-ray bursts (GRBs) detected by the RHESSI
satellite is studied statistically. We focus on GRB duration and hardness ratio
and use the statistical chi^2 test and the F-test to compare the number of GRB
subgroups in the RHESSI database with that of the BATSE database. Although some
previous articles based on the BATSE catalog claim the existence of an
intermediate GRB subgroup, besides long and short, we have not found a
statistically significant intermediate subgroup in the RHESSI data.
