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A study was carried out to develop and validate models that simulate grapevine phenology of the cultivars Cabernet Sauvignon, Merlot, Chardonnay and Sauvignon Blanc growing under Mediterranean climate conditions. In this study, phenology models were developed using a monomolecular equation, where the dependent and independent variables were the Eichhorn and Lorenz (1977) phenological (ELP) scale modified by Coombe (1995) and growing degree days (GDD), respectively. From the beginning of budburst to harvest, measurements of ELP and GDD were collected weekly from 49 commercial vineyards located in the Maule Region, Chile (between 34 degrees 40' and 36 degrees 33' south latitude, 72 degrees 38' and 70 degrees 18' west longitude). The results showed significant nonlinear correlations between the GDD and ELP scale, with values of R-2 ranging between 0.95 and 0.98. Moreover, the validation indicated that the phenological models were able to predict the ELP scale with values of the root mean square error (RMSE), mean absolute error (MAE) and agreement index (dr) raging between 1.6-3.0, 1.3-2.5 and 88-89%, respectively. Major disagreements were observed near the harvest stage (ELP = 40) which mainly depends on farm management.