A total of 96 hybrids from four maturity groups (FAO 200, 300, 400, 500) were tested in two years (2006, 2007) at two locations in Hungary (Martonvásár, Szarvas). Considerable differences were found between the years for the grain yield per hectare and for the grain quality parameters. In 2006 record yields were achieved at both locations, averaging 11.61 t/ha in Martonvásár and 12.20 t/ha in Szarvas, due primarily to well-timed irrigation in Martonvásár and to good rainfall supplies in Szarvas. In 2007 both locations suffered from drought, with less rainfall than average during the critical months of the vegetation period, which was partially compensated for by irrigation in Martonvásár, giving a yield average of 5.96 t/ha, while the hybrids grown in Szarvas had a yield average of 5.06 t/ha. The grain quality parameters exhibited a close correlation with the grain yield in the individual FAO maturity groups. Hybrids of the flint type, which have a short vegetation period, had high protein and oil contents, but the yield averages were low due to the slower rate of starch incorporation. Hybrids of the dent type have a longer vegetation period and more intense carbohydrate accumulation, but low protein and oil contents. In wet years and locations there was a higher rate of starch accumulation, while dry years are favourable for protein and oil accumulation. The Bravais correlation coefficient was calculated between the yield and the grain quality parameters (averaged over years, locations and varieties). A positive, moderately strong correlation (0.68) was found between the yield and the starch content, a negative, moderately strong correlation (-0.52) between the yield and the protein content, and a loose negative correlation (-0.19) between the yield and the oil content.