The parameters determining the agronomic and economic performance of genetically modified maize hybrid MON 89034 × NK603 and conventional hybrids were compared under conditions that eliminated the herbicide tolerance in GM hybrid as well as the use of insecticides in conventional hybrids. The GM hybrid confirmed ability to protect itself against the European corn borer and its average grain yield was higher by 6.36-14.42% (i.e. 0.82-1.86 t/ha) in comparison with conventional hybrids. The year of cultivation statistically significant influenced agronomic parameters and the financial income of maize production. The maize genotype did not statistically significantly affected any evaluated parameter. The final income was statistically significant (P < 0.05) negatively influenced by all observed agronomic parameters with the exception of the seed price. The price of maize grains on the market was the only one factor that statistically significant (P < 0.05) influenced financial income of the maize production.