Modeling the drastic change in population during this modern era has become the major
interesting area among the demographers of the world, particularly of the developing
countries. Usually, the exponential and time series models are exercised for overall
population projection. These models seem lacking in projecting the population age
distribution. The population age distribution projection has its own practical importance for
several reasons in policy making. This article investigates the projection of population age
distribution of Pakistan as well as the disparity index of the projected and census of
populations. A Markov Chain (MC) model has been developed to project the population of
different age groups and found to be parsimonious. The population age distribution is
projected up to 2021 using 1972 and 1981 census populations to calculate the probabilities
of survival. The Gini coefficients and Lorenz curve are also estimated to examine the
disparity of projected and census populations. The findings demonstrated the mild level of
disparity within the population census1972; 1981; 1998. The disparity measures of
projected population age distribution for the year 2011 and 2021 are approximately same as
that of 1998 population census. The results indicated that the population age distribution
pattern would not be changed drastically if the social behavior of the society continues
similar to the patterns reflected by the year 1998. However, the projection also anticipated
about the decrease in 0-4 age group and increase in ageing population.