In this paper, the most important analytical methods applied in detection of genetically modified food are presented. Most of the techniques are based on identification of changes in structure of two biological active macromolecules: DNA and proteins. In case of nucleic acid, basic diagnostic tool is polymerase chain reaction (PCR), used in selective amplification of specific DNA fragments with qualitative and quantitative analysis of introduced modifications. Real-time PCR is actually established as a primary method in analysis of the contents genetically modified organisms in transgenic crops and foods. To estimate the genetic modification manifested on protein structure level there are introduced immunoenzymatic assays based on selective recognition of recombinant protein by specially designed antibody. Although simplified form with recognition of antigen-antibody complex on nitrocellulose strip and classic version of immunoenzymatic assay on microplate are mainly treated as qualitative methods. Together with the development of genetic manipulation, numbers of plant transformations are growing and probably, in the near future also animal transformations, there is a need to establish reliable tests for detection and quantification of several genetic modifications in a single analysis.