This book describes findings of the study made to find out the possible effects of climate change on Boro rice, a major food grains that comprise about 60% of rice production in Bangladesh. Simulation results indicate that growth and yield of rice are directly related to temperature, CO2 concentrations, water requirement and planting dates etc. Temperature effects significantly on rice yield and the effect would be more pronounced if temperatures rise in 4°C. Very high temperatures have been predicted for the years 2050 and 2070 due to climate change which would cause yield reductions over 15 to 60 percent. Planting date also showed similar result and this would become more in future with rise of temperatures. CO2 concentrations have a positive impact on rice yield although higher level in future would compensate the adverse effects of increased temperatures to some extent, but it would not be able offset overall impact. Climate change causes significant reduction in rice yields. Development of improved cultivars suitable to withstand high temperatures (2°C to 4°C) and tolerant to water stress may mitigate the production problems projected for the next 50 to 100 years.