Fermi-LAT observations have proven that GeV γ-ray emission is a relatively common feature for many Gamma Ray Bursts (GRB). However the low effective area of space detectors implies low statistics for high energy photons which prevent any physical interpretation at such energy range. The current generation of Imaging Atmospheric Cherenkov Telescopes (IACTs) array of > 104 m2 effective area above a few tens of GeV is able to detect higher energy photons.
The High Energy Stereoscopic System (H.E.S.S.) is one of the current generation of IACTs. The large light collection area of the largest telescope and its fast slewing make it perfectly suitable to observe γ rays below 100 GeV with an unprecedented sensitivity. Several tens of GRBs have been observed since 2007. This contribution is about the results of this large sample of observation above a few tens of GeV.