  Electron-positron annihilation radiation from the Galactic Center region has
been detected since the seventies, but its astrophysical origin is still a
topic of a scientific debate. We have analyzed data of the gamma-ray imager
IBIS/ISGRI onboard of ESA's INTEGRAL platform in the e$^{-}$e$^{+}$ line.
During the first year of the missions Galactic Center Deep Exposure no evidence
for point sources at 511 keV has been found in the ISGRI data; the $2 \sigma$
upper limit for resolved single point sources is estimated to be $1.6\times
10^{-4} ph cm^{-2} s^{-1}$.
