Reliable small-plot experiments play an important role in determining the value of hybrids, but the results of large-plot experiments, which give a better reflection of conditions and technologies, are needed to obtain reliable information on which hybrids can be produced most economically under specific cultivation conditions. Within the framework of the National Research Development Programme, large-scale tests are underway on new Hungarian maize hybrids, to promote the selection, introduction and propagation of the most economical hybrids for specific regions, ecological conditions and technological standards. The tests included hybrids Sze SC 271 (FAO 290), Dáma (FAO 300) and Mv 277 (FAO 320) from the very early maturity group, Sze SC 352 (FAO 340), Hunor (FAO 370) and Norma (FAO 380) from the early maturity group and Maraton (FAO 450) and Sze SC 463 R (FAO 490) from the medium maturity group, grown at 20 different locations in Hungary. Each year the yield differences between the locations reflected the extreme distribution of precipitation during the growing season in different parts of the country. High amounts of precipitation were required in the growing season to reach the highest yields, but moderately high yields were achieved over a wide range of rainfall levels.