I talian processed tomato has a major dominance at the global level but few studies have been conducted using a cropping systems analysis approach for this crop.The objective of this research was to evaluate the Cropping System Model (CSM)-CROPGRO-Tomato of the DSSAT (Decision Support System for Agrotechnology Transfer) software with experimental data obtained from field studies conducted in Legnaro, northeastern Italy in 2009 and 2010. The experiment encompassed four transplanting dates with ten-day intervals from 22nd March (TD1, 2, 3, and 4), and two processing tomato varieties (Augusto F1 (De Ruiter), and NPT 63 (S & G)) comparing mulched and non-mulched plots. A comparison of yield for the different transplanting dates showed that earlier transplanting increased yield for both varieties, there was a variation in yield between varieties in both years. Calibration of CSM-CROPGRO-Tomato model using non-mulched data of 2009 showed that index of agreement (d-Stat) between observations and model simulation for different parameters (total dry matter, fruits fresh and dry weight, vegetative dry matter, number of fruits, harvest index and leaf area index) using both varieties ranged from 0.562 to 0.964 at TD1, from 0.915 to 0.992 at TD2, from 0.566 to 0.990 at TD3, and from 0.733 to 0.998 at TD4. Values of d-Stat for model calibration were lower for leaf area index, which ranged from 0.511 to 0.924. Model calibration using TD1 gave acceptable simulation, whereas it was quite high with the other transplanting dates. CSM-CROPGRO-Tomato model could be used as a decision-making tool helping in regional short term plans.