The compact muon solenoid first physics results

In November and December 2009, the LHC delivered the first proton-proton collisions with beams of 450 GeV and then of 1.18 TeV, an unprecedented energy. On the 30th of March 2010, LHC operation moved forward to the physics era with collisions at a 7 TeV center of mass energy and, by the time of the IPRD10 conference, an integrated luminosity of 20 nb^-^1 was accumulated. This paper relates how the CMS data reconstruction and Monte-Carlo simulations were validated in only few months. It presents th e first physics results.