An express assay for screening of potato transformants by their GFP fluorescence intensities is developed. In comparison to the widely used methods of transgenic plant screening by PCR, Real-Time RTPCR or Northern-blotting, the GFP fluorescence assay needs no expensive reagents and takes less time. This approach may also be used for nondestructive screening of the T0 transgenic regenerants which can be further grown and used. To prove this assay reliability, the expression of the hGFP gene in the leaves of transgenic potato (cv. Skoroplodny) plants, determined by its mRNA accumulation, was compared to GFP fluorescence intensity in the micro-samples of aseptic plant leaves. The strong correlation between the results of these two methods is the evidence of positive dependence of GFP fluorescence intensity on the target mRNA content.