Studies of the impact of terahertz radiation on living objects present a significant interest since its use for security systems is currently considered promising. We studied the non-thermal impact of terahertz radiation on E. coli/pKatG-gfp biosensor cells. The Novosibirsk free electron laser (NovoFEL), which currently has the world's highest average and peak power, was used as the source of terahertz radiation. We demonstrated that exposure to terahertz radiation at the wavelengths of 130, 150, and 200 µm and a power of 1.4 W/cm2 induces changes in green fluorescent protein (GFP) fluorescence values and thus induces the expression of GFP in E. coli/pKatG-gfp biosensor cells. Possible mechanisms of the E. coli response to non-thermal exposure to terahertz radiation are discussed. Bioelectromagnetics 34:15–21, 2013. © 2012 Wiley Periodicals, Inc.