In this paper we project the population of Bangladesh by sex and age group from 2002 to 2031 based on a two parameter negative exponential model. It has been observed that a two parameter negative exponential model is suitable for the age patterns of population of Bangladesh for both, male and female. Data for this study comes from 1991 and 2001 population census of Bangladesh. The model validation technique crossvalidity prediction power (CVPP) is applied to check on the validity of the model. The observed values of 1991 and 2001 are used to estimate the inter censual annual exponential growth rate by age groups. Finally, age specific inter censual annual growth rates are used to project the population of Bangladesh by sex and age group, considering 2001 census population as base population and assuming fertility and mortality remain constant during the projected period. The population of Bangladesh is projected to increase from 123.9 million in 2001 to 193.7 million in 2031, an increase of 56.39 percent during the projected period. Male population will increase from 63.9 million in 2001 to 100.0 million in 2031, and female population will increase from 60.0 million in 2001 to 93.7 million in 2031, an increase of 56.47 and 56.3 percent, respectively.