Doubly resonant Z pair production with DELPHI

Since 1997 until the end of its operation in 2000, the LEP accelerator was working at a center of mass energy above the kinematic threshold for doubly resonant Z pair production. This made it possible to measure this cross section with high precision and statistical significance. The results obtained in different final states analyzed by DELPHI are briefly presented here. Combining all different final states and energies, an averaged cross section with respect to the standard model (SM) expectation is derived and gives 1.04+or-0.12(stat.) * SM which agrees very well within statistical uncertainty. (10 refs).