We present a brief account of the difficulties involved in detection of oxygen free radicals in plants and give a rationale for using the EPR spin trapping technique in such studies. Comparative analysis of characteristics of different spin traps is given, having in mind their suitability in trapping oxygen-centered free radicals. Certain technical aspects of EPR experiments related to successful trapping of free radicals are discussed. Previous studies of trapping of oxygen radicals in plants are reviewed in terms of how efficient the experimental approach employed has been in their detection and how this influences conclusions about the mechanisms of their production. In addition, we analyze the potential of spin labels in the analysis of free radical production in plants and demonstrate that the combination of EPR spin traps and spin labels is extremely efficient for this purpose.