Under optimal conditions it is expected that grain yield correlates positively, at least to some point with the biological yield, respectively the yield of above-ground dry biomass. But, the influence of different growing factors affects this correlation. In this respect, the aim of the paper was to present the results we have obtained at maize in South Romania at different hybrids and under different growing conditions (different environmental and technological conditions) regarding the correlation of the yield of grains with the yield of dry matter. In view to achieve this aim, field experiments were performed in 2012 and in 2013 in different locations from South Romania. In 2012, ten maize hybrids were studied in four locations, while in 2013 five maize hybrids were studied in two locations, which represented different soil and climatic conditions. Moreover, in 2013 each studied hybrid was studied under three row spacing (75 cm, 50 cm, and twin-rows of 75/45 cm) and three plant densities (60,000, 70,000, and 80,000 plants ha(-1)). Under climatic conditions of 2012 and in different locations from South Romania, the yield of grains of the studied maize hybrids correlated positively with the yield of dry matter. At different row spacing and plant populations, the yield of grains correlated differently with the yield of dry matter according to growing conditions.