ATLAS has recorded 30 nb-1 of proton-lead data and 140 µb-1 of lead-lead data during Run I. The multi-purpose detector, designed for proton-proton interactions, has shown an excellent performance in heavy ion collisions and provided a wide research program with the aim of studying the properties of QCD matter at extreme temperatures and densities. Results on bulk phenomena, including charged particle measurements and collective flow, and on hard probes, including single muons, high p_T hadrons and jets, will be presented.
