The cycles of the water isotopic species (HDO and (H2O)-O-18) have bee
n incorporated in three atmospheric General Circulation Models (GCMs)
with the main objective of predicting the distribution of water stable
isotopes in precipitation. The performances of those models are exami
ned for present-day climate through a comparison with existing data av
ailable from the IAEA/WM0 network established in 1961 and from other s
ources.