Genetically Modified (GM) insect resistant (Bt) maize crops have been grown commercially in the European Union (EU) since 1998, and in 2006, there were plantings in seven EU member states.  This paper reviews the specific economic impacts on yield and farm income as well as the environmental impact in respect of insecticide usage (where data exists).  The analysis shows that there have been important yield and net economic benefits at the farm level equal to an improvement in profitability of between 12 and 21%.  Where farmers have previously used insecticides to control pests, the technology has reduced insecticide spraying and as a result decreased the associated environmental impact.  Bt maize has also delivered important improvements in grain quality through significant reductions in the levels of mycotoxins found in the grain.