The influence of demographic factors on public infrastructure investments in South-South Nigeria was empirically assessed in this study with the primary purpose of ascertaining the extent of consideration of demographic factors in budgetary planning. The specific study variables are government capital expenditure, as dependent, and demographic factors (per capita government revenue, population density, population, and number of households), as independent variables. Secondary data were collected from annual budgets of governments, the population commission and Bureau of Statistics of Nigeria, Publications of the Central Bank of Nigeria, and few research articles containing relevant public records. The 6 states of the South-South region of Nigeria are taken as the population of the study which covers a period of 11 years (2007-2017). The data were analysed employing multiple regression statistical method. The study reveals at 5 % level of significance, that no significant relationship exists between aggregate