Plant density and nitrogen (N) fertilizer responses of one local and three improved open-pollinated cultivars of maize (Zea mays L.) developed in different eras of maize breeding were studied on sandy-loam Alfisols in the Guinea savanna zone of Ghana in 1992 and 1993. A split-plot design was used in which plant densities (30 000, 50 000, 70 000 plants/ha) were the main-plots and 12 combinations of N fertilizer levels (0, 80, 160 kg N/ha) and cultivars (Local, Composite 4, Dobidi, Okomasa) were the sub-plots in four replicates. A cross location analysis for grain yield showed environment, plant density, nitrogen and cultivar effects were highly significant (P