Bangladesh is one of the countries most vulnerable to climate change impacts such as extreme weather events, due to its low-lying topography, high population density and widespread poverty. In this paper, we report on the development and results of an agent-based model of the migration dynamics that may arise in Bangladesh as a result of climate change. The main modules are each calibrated with data on relevant indicators, such as the incidences of extreme poverty, socioeconomic vulnerability, demography, and historical drought, cyclone and flood patterns. The results suggest likely changes in population densities across Bangladesh due to migration from the drought-prone western districts and areas vulnerable to cyclones and floods in the south, towards northern and eastern districts. The model predicts between 3 and 10 million internal migrants over the next 40 years, depending on the severity of the hazards. Some associated policy considerations are also discussed.