  The ICARUS T600 detector, with its 470 tons of active mass, is the largest
liquid Argon TPC ever built. Operated for three years in the LNGS underground
laboratory, it has collected thousands of CNGS neutrino beam interactions and
cosmic ray events with energy spanning from tens of MeV to tens of GeV, with a
trigger system based on scintillation light, charge signal on TPC wires and
time information (for beam related events only). The performance of trigger
system in terms of efficiency, background and live-time as a function of the
event energy for the CNGS data taking is presented.
