This paper focuses on the adjustment of reported populations from censuses in developing countries. Reported populations by sex and 5–year age groups in censuses from developing countries are known to be defective and need adjustment before they can be gainfully utilised. We apply methods based on population models to obtain adjusted populations from the reported populations because mathematical methods have been shown to smoothen out genuine features of a study population. In order to assess the success of the adjustment, the adjusted data were subjected to re-evaluation and were used to obtain estimates of some demographic parameters (fertility, mortality, etc). Using the age-sex accuracy index, the results show that quality of the adjusted populations improved substantially in all the censuses and appear much better than results from the mathematical methods. Therefore, we recommend that, where necessary, adjusted data using population models should be used for estimation of demographic parameters and population projections in developing countries.