Understanding of CO2 and its interactions with other important environmental and management variables is required for a more complete understanding of the effects of elevated CO2. The Oryza2000 model was evaluated with experimental data from three years of FACE experiments conducted in 1998 through 2000. In this experiment rice plants were subjected to elevated [CO2] under varying nitrogen (N) fertilization rates in farmers' rice paddies in Japan. Higher N rates increased peak green leaf area index (GLAI) for all three years but small increases with increased CO2. The model with the default set of parameters overestimated GLAI for all CO2 and N levels. Except for the moderate overestimation for 2000, the model was able to capture the observed biomass despite its large overestimation of GLAI. In the field experiment, increasing N and CO2 resulted in higher grain yield, which was simulated by the model without large biases. A comparison between the observations and the simulations with the original model parameter values showed that leaf mass fraction (LMF) was simulated reasonably well, but that root-to-shoot ratio (R:S) and SLA were overestimated. Changes in the model parameter values to correct for the overestimation of R:S and SLA improved the simulation of plant growth under ambient [CO2], whereas further changes required to account for the effect of elevated [CO2] on SLA and LMF. In contrast to the observation, simulated fractional increase in yield caused by elevated CO2 was slightly higher for low nitrogen (LN) crops. Further model improvement requires enabling the model to realize rice cultivars differences specially on relation between crop total N uptake up to panicle initiation and spikelet number per unit ground area, investing N on either higher leaf area or amount of N per leaf area, and low threshold of N amount which triggers N stress effects.