Concerns about genetically engineered crop plants are focused on three potential risks: (1) that transgenic crop plants will become aggressive weeds of agricultural fields or invasive in natural habitats; (2) that their engineered genes will be transferred by pollen to wild relatives whose hybrid offspring will then become more aggressive or invasive; or (3) that the transgenic crops will be a direct hazard to humans or domestic animals. The focus of our work is on the second of these risks, that of gene flow from a genetically engineered crop, strawberry, to a related wild species. Utilizing the molecular marker technology of Amplified Fragment Length Polymorphism (AFLP) and direct studies of the fitness of laboratory produced hybrids, we have documented that hybrids between cultivated and wild F. virginiana occur commonly and that they are highly fit, with the potential to persist and reproduce. In our molecular marker analyses, we have confirmed that F. virginiana populations near strawberry farms in our region contain substantial numbers of hybrid plants displaying DNA markers from cultivars currently grown cultivars no longer grown in our region. Additionally, studies of chloroplast DNAs polymorphism have allowed us to evaluate the contribution of seed dispersal versus pollen dispersal mechanisms for gene escape. Strawberries, unlike many crops, are perennial and clonal, and both these traits increase the risks of hybridization, introgression, and persistence. Our research is measuring the additional effects of these two life-history traits, and should provide guidance on how best to mitigate the risks of transgene escape from strawberries and perhaps from other outcrossing perennials as well.