Bangladesh is one of the twenty developing countries with largest number of elderly population. By 2025 Bangladesh along with four other Asian countries, will account for about half of the world''s total elderly population (East-West Center, 2002; Conception, 1987). Using simple methods such as exponential or geometric method one can carry out population projection. But these methods do not provide realistic estimates because it is based on the growth rate of the population. Cohort-Component method is the best method of projecting future population because it takes into account of all the components of population growth. This book, therefore, utilized cohort-component method of population projection. The objective of this book is to present an overview of the existing methods for population forecasting and to propose an alternative based on the Bayesian statistics, combining the formality of inference. The analysis has been made using MCMC technique for Bayesian methodology available with the software WinBUGS. Convergence diagnostic techniques available with the WinBUGS software have been applied to ensure the convergence of the chains necessary for the implementation of MCMC.