Introgression from genetically modified plants (GMPs) may be dependent on the genetic similarity to wild relative plants. In Korea, many wild plant species are botanically related to the cultivated plants that have a potential to be genetically transformed. The controversy for hazards of GMPs is continuing because the studies on gene flow or introgression are little. Based on the systematic criteria, we have surveyed Korean wild plant species that showed the similarity to cultivating crops. The consideration for feasibility of genetic pollution (introgression of transgene) is necessary for the successful accomplishment in the practical use of GMPs. Although the detrimental effects of GMPs on wild relatives have not been clearly verified, Korean wild plant species related to crop plant (potential GMP) have to be investigated with respect to the introgression. Korean flora consists of ca. 5,500 species. Among them, 1,448 species are classified as weed species (966 native, 325 naturalized, and 167 escaped ones), which is vulnerable to GMPs in term of introgression. We suggested the principal Korean wild plants related to major crops that might be affected by GMPs via introgression. The investigated species herein are selected based on the morphological and phenological relationship. It is necessary to verify the genetic relationship between cultivated plants and wild relatives sing more precise molecular techniques, which provide the information of likelihood for the introgression of transgene.