We obtained estimates for Niamey’s 2004 population size from each of the following sources: Médecins Sans Frontieres (MSF), The Ministry of Health (MoH) of Niger, and the United Nations (UN), as summarized in Table 1. All three estimates were projections from the 2001 census. Note that MSF used a 2001 population size of 70795130 with an annual growth rate of 4.8%, calculating a total population size of 769454; our calculations using the described methodology yielded a larger total.