||The genetic variability of five promising tropical and tropical-temperate maize populations introduced or developed in Benin was studied for grain yield components (number of grains per ear and grain weight). The populations are: EV8443SR, an elite tropical population and four tropical-temperate populations (F1 and BC1 of two crosses between EV8443SR and the temperate populations FS14 and DEA): EV8443SR x FS14 (EF), EV8443SR x (EV8443SR x FS14) (EFE), EV8443SR x DEA (ED), and EV8443SR x (EV8443SR x DEA) (EDE). Random sets of S1 families of the populations were evaluated in two tropical locations (savanna and forest zones) in Benin using 12 x 12 triple lattices. No significant difference among population genetic variances was observed in any of the two crosses studied. For number of grains per ear, the highest expected genetic progress was obtained in the population EF in cross EV8443SR x FS14 and in the population EDE in cross EV8443SR x DEA. For grain weight, the highest genetic progress was obtained in the 50% tropical 50% temperate population (EF or ED) in savanna zone and in the tropical parent EV8443SR in forest zone. EV8443SR appeared better than, or practically equal to the tropical-temperate populations, as a foundation population to increase number of grains per ear and grain weight.