The Borexino experiment at the Gran Sasso Laboratory is in data taking since May 2007.Borexino makes use of about 280 tons of high purity organic liquid scintillator to measure in real-time sub-MeV solar neutrinos. 7Be and 8B solar neutrinos have been measured with a massive liquid scintillator. Besides solar neutrinos, Borexino has measured the signal of electron anti-neutrinos from nuclear reactors and from the Earth, so-called geo-neutrinos. No events of electron anti-neutrinos have been detected above about 7 MeV and this allows to determine bounds on the neutrino - anti-neutrino transition and on SRN's. Details of the antineutrino analysis will be presented in this talk.