  The $ZZ$ production cross section in proton-proton collisions at 13 TeV
center-of-mass energy is measured using 3.2 fb$^{-1}$ of data recorded with the
ATLAS detector at the Large Hadron Collider. The considered $Z$ boson
candidates decay to an electron or muon pair of mass 66-116 GeV. The cross
section is measured in a fiducial phase space reflecting the detector
acceptance. It is also extrapolated to a total phase space for $Z$ bosons in
the same mass range and of all decay modes, giving
$16.7^{+2.2}_{-2.0}$(stat.)$^{+0.9}_{-0.7}$(syst.)$^{+1.0}_{-0.7}$(lumi.) pb.
The results agree with standard model predictions.
