  Measurements of on-shell ZZ production are described, using data from the
DELPHI experiment at LEP in e+e- collisions at centre-of-mass energies between
183 and 209 GeV, corresponding to an integrated luminosity of about 665
pb^{-1}. Results obtained in each of the final states q anti-q q anti-q, nu
anti-nu q anti-q, mu+ mu- q anti-q, e+ e- q anti-q, tau+ tau- q anti-q, l+ l-
l+ l-, and nu anti-nu l+ l- (with l=e,mu) are presented. The measured
production cross-sections are consistent with the Standard Model expectations.
These results update and supersede those already published at 183 and 189 GeV.
