There is a near-consensus in the literature that urbanization is incompatible with large family size owing to factors such as high cost of urban living, opportunity cost of having children in urban centers and increasing awareness of benefits of small family size. However, a cursory glance at the data on sub-Saharan Africa cast doubt on the incompatibility of urbanization with high fertility rate. Hence, this paper investigates the urbanization-fertility nexus in the two most urbanized countries of SSA – Nigeria and South Africa. Exploiting time series data for both countries within a Fully Modified Ordinary Least Square (FMOLS) framework, the incompatibility hypothesis is refuted in both countries. Specifically, the analysis suggests that in Nigeria and South Africa, increasing degree of urbanization is positively related with fertility rate with the magnitude of the relationship being higher in Nigeria than South Africa. These findings imply that policies aimed at improving urbanization process and reducing fertility rates are crucial in both countries.