Some articles based on the BATSE gamma-ray burst (GRB) catalog claim the existence of a third population of GRBs, besides long and short. In this contribution we wanted to verify these claims with an independent data source, namely the RHESSI GRB catalog. Our verification is based on the statistical analysis of duration and hardness ratio of GRBs. The result is that there is no significant third group of GRBs in our RHESSI GRB data-set.