  The IBIS imager on board the INTEGRAL satellite, thanks to the large field of
view and good sensitivity, gave us a unique opportunity to search for possible
511 keV point sources either previously unknown or associated to known objects
such as X-ray binaries or supernovae. The IBIS sensitivity at 511 keV depends
on the gamma ray detector quantum efficiency at this energy and on the
background. Both these quantities have been estimated. Reducing all the
available IBIS data up to April 2008 we have produced a 5 years full sky 511
keV map with 10 Ms exposure in the Galactic Center. We did not find any
significant signal at this energy. The lack of detection of 511 keV galactic
point sources is in agreement with the idea that a significant part of the
galactic positrons originates in compact objects and then propagates in the
interstellar medium.
